Aluminum Alloy Samples Research Articles

Effect of cutting parameters on the corrosion resistance of 7A04 aluminum alloy in high speed cutting

This work aims to explore the effect of cutting parameters on the corrosion resistance of 7A04 aluminum alloy in high speed cutting. First, 7A04 aluminum alloy samples are subjected to short-range solution treatment under 470 °C/1 h and 490 °C/20 min, followed by double-stage aging treatment under 120 °C/3 h + 160 °C/3 h. After heat treatment, the samples are experimentally cut at high speed for single factors to investigate how cutting parameters affect the EIS, polarization curve, and corrosion morphology of 7A04 aluminum alloy in high speed cutting. The results show that for 7A04 aluminum alloy treated by solution treatment 470 °C/1 h, cutting speed 1400–1550 m/min, cutting depth 1.5–2.0 mm and feed rate 0.10–0.12 mm/tooth can yield better corrosion resistance with larger capacitance arc radius, more positive Ecorr, smaller Icorr and R, larger Rp, and fewer corrosion products. For 7A04 aluminum alloy treated by solution treatment 490 °C/20 min, cutting speed 1550–1700 m/min, cutting depth 1.5 mm and feed rate 0.12 mm/tooth can yield better corrosion resistance with larger capacitance arc radius, more positive Ecorr, smaller Icorr and R, larger Rp, and fewer corrosion products. Machined surface with more surface scratches correspond to more corrosion products, whereas adhesive chips and pits are less relevant with corrosion products. EDS analysis reveals that the corrosion products are primarily Al(OH)3 insolubles. Under the same cutting parameters, 7A04 aluminum alloy treated by solution treatment 490 °C/20 min is more corrosion resistant.

Development of High Strength and High RRR Aluminum-Stabilizer for Superconducting Cable in CEPC Detector Magnet

For the development of a large-aperture superconducting detector magnet in circular electron-positron collider (CEPC), super-conducting cables consisting of Nb-Ti/Cu wires and aluminum stabilizer are essential in both handling large electromagnetic forces during normal operation and redistributing the operation current of tens of kiloampere in case of a quench. High-purity aluminum stabilizer offers extremely high residual resistivity ratio (RRR) for quench protections, however, is too ductile to withstand huge Lorentz forces. Doping technology have been studied in detail in this paper to improve the yield strength of 4N8-aluminium (99.998%) while minimizing the reduction of RRR. All aluminum-alloy samples are characterized by a GM cryocooler for the measurement of RRR and by the standard tensile test facility for the measurement of 0.2% yield strength. It is found that by doping in Ni-0.025% Be-0.025%, annealing at 430 °C, cold-working hardening (∼21%), and curing at 130 °C for 15 h, the resultant aluminum alloy obtains an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p0.2</sub> of 75 MPa at room temperature and a RRR of 417, meeting the basic design requirements of the superconducting detector magnet for CEPC.

Study on wear resistance of local aluminum alloy reinforced by carbon fiber transfer membrane region

In order to study the effect of fiber reinforced resin matrix composites on the friction properties of aluminum alloy, 7075 aluminum alloy, Carbon fiber reinforced plastic (CFRP) and 7075-Al/CFRP hybrid samples were selected for pin-disk friction test. White light interference and scanning electron microscopy were used to analyze the surface morphology of the friction samples. Secondly, the formation process of the transfer membrane was analyzed by Raman test and energy spectrum. Finally, the strength of the transfer film was verified by scratch test. The results showed that the friction coefficients of 7075-W and 7075-T6 aluminum alloy are 0.419 and 0.398, and the wear rates are 0.288% and 0.273%, respectively. For CFRP and 7075-Al/CFRP hybrid samples, the microscopic study of friction interface showed that CFRP and aluminum alloy abrasive particles exchanged elements under the dual action of pressure and shear force, thus forming Transfer Membrane Region (TMR). TMR with strong self-lubrication preferentially supported the friction load during the friction process, thus reducing the friction and wear of aluminum alloy. The friction coefficient and the wear rate of the 7075-Al/CFRP hybrid sample were reduced by 62.5% and 78.2%, respectively in comparison to pure 7075 aluminum alloy sample.

Enhanced boiling heat transfer of water on a liquid-infused surface

The aim of this study was to experimentally demonstrate a counter-intuitive phenomenon that a surface covered with a liquid has the potential for enhancing heat transfer for the boiling of water over it. To this end, a highly-wetting surface with a zero contact angle for multiple liquids, i.e., an Ultra-Omniphilic Surface (UOS) was prepared on aluminum (Al 6061 alloy) using a simple and easy-to-implement bulk micro-manufacturing approach and a non-boiling liquid (NBL) was infused over this surface to occupy its sub-surface micro/nano-cavities. The resulting liquid-infused UOS is called a Binary Surface (BiS) for it has two distinct superficial phases — solid phase as islands and liquid phase as NBL puddles. Saturated nucleate pool boiling experiments were conducted on the BiS and the critical heat flux (CHF) and the boiling heat transfer coefficient (HTC) were measured. The results were compared with the UOS and a plain/polished surface (PS) prepared from the same aluminum alloy sample. In addition, high-speed visualization was employed for capturing the bubble dynamics at different heat fluxes and parameters such as bubble departure diameter (Dd), bubble departure frequency (f), and nucleation site density (NSD) were measured. The results revealed that the nucleate pool boiling performance of water on the BiS surpasses both the PS and the UOS. The HTC on the BiS was 1.33 times and two times larger than the UOS and the PS, respectively. The CHF obtained on the BiS was comparable to that on the UOS and 1.47 times larger than that on the PS even though a considerable portion of the BiS surface area was covered with the NBL and unavailable for boiling. Remarkably, an inspection of the high-speed videos has suggested the presence of the same NBL as the reason for the better boiling heat transfer performance of the BiS. The NBL that was spread over the BiS as puddles was found to (1) prevent the growth of large vapor bubbles and (2) extend the isolated bubble regime by delaying the lateral coalescence of adjacent bubbles. A comparison of the results between UOS and BiS suggests that – as far as boiling enhancement is concerned – mechanisms for tackling vapor bubbles could be superior to those that involve improving surface wettability.

Corrosion mechanism and machinability of 7075‐T6 aluminum alloy in high‐speed cutting: With and without cryogenic treatment

AbstractThis work aims to explore the effect of cutting parameters on the cutting force, surface quality, and corrosion resistance of 7075‐T6 aluminum alloy after and without cryogenic treatment. Cryogenically treated (T6‐C) and noncryogenically treated (T6) 7075‐T6 aluminum alloy samples are experimentally cut and electrochemically corroded in a 3.5% NaCl solution. SEM, EDS, and electrochemical analysis are carried out to examine how cutting parameters affect the cutting force, surface quality, and corrosion resistance of cryogenically treated 7075‐T6 aluminum alloy. The results show that after cryogenic treatment, under different cutting speeds, the cutting force is up to 39.8% smaller than without cryogenic treatment; under different cutting depths and feed rates, the cutting force is up to 136% and 21.54% smaller, respectively. Cryogenic treatment dramatically reduces the cutting force in the cutting process. As cutting speed increases, machined surface quality becomes better; fewer corrosion products and cracks are induced. When the cutting depth is 1.5 mm, there are fewer plows and micro‐cracks on the machined surface than under other parameters, but cutting depth does not affect corrosion morphology significantly. The size of corrosion products is up to 55 μm smaller. The electrochemical analysis finds that at the cutting speed of 1500 m/min, after cryogenic treatment, the current density is 59.4% smaller than without cryogenic treatment; polarization resistance is 1.68 × 105Ω•cm2 larger. At the cutting depth of 1.5 mm, after cryogenic treatment, the current density is 66.16% smaller; self‐corrosion potential shifts 0.19 V toward the positive pole. At the feed rate of 0.06 mm/z, after cryogenic treatment, self‐corrosion potential shifts 0.18 V toward the positive pole; polarization resistance is 10.7% larger. These parameters correspond to the best corrosion resistance.

Three-dimensional annular heat source for the thermal simulation of coaxial laser metal deposition with wire

Coaxial laser metal deposition with wire (LMD-w) is an innovative additive manufacturing technology in which a wire is coaxially fed through the center of a hollow laser beam into a laser-induced melt pool. This special configuration results in a direction-independent process, which facilitates the manufacturing of thin-walled metal components at high deposition rates. However, laborious experimental test series must be conducted to adjust the process parameters so that the substrate and the part do not overheat. Therefore, models are needed to predict the resulting temperature field and melt pool dimensions efficiently. This paper proposes a finite element simulation model using an innovative heat source, which considers the unique intensity distribution of the annular laser spot. The heat source parameters were calibrated experimentally based on fusion lines obtained from metallographic cross sections of aluminum alloy samples (AA5078 wire and AA6082 substrate). Subsequently, the temperature distribution in the substrate plate was measured by means of thermocouples to validate the developed model. It was shown that the proposed heat source replicates the heat input accurately. With the presented model, essential features for process development, such as the temperature field and the melt pool dimensions, can be reliably predicted. The model contributes to a better understanding of the LMD-w process and facilitates an efficient process development in future research work as well as for industrial applications. Key words: thermal simulation, annular laser spot, heat source, laser metal deposition, coaxial wire feeding, directed energy deposition

Mechanical and corrosion characteristics of 6061–T6 aluminum alloy samples reinforced with alumina micro and nanoparticles fabricated by friction stir processing

The present study investigates the mechanical and corrosion properties of reinforced 6061[Formula: see text]T6 aluminum samples after friction stir processing. Three different composites are fabricated: one without any powder and the others with micrometer and nanometer alumina powder (Al2O3) as reinforcing particles. The hardness, tensile, and potentiodynamic polarization tests are performed to compare the new samples with the base metal. The results show that friction stir processing has increased the tensile and ultimate strength of the composites by an average of 181% compared to the base metal which is due to the microstructure changes including grain distribution refinement and the elimination of defects and micro-voids through localized plastic deformation. The strength of the composites with additives is significantly affected by the size of the particles. The hardness of the processed samples has also increased compared to the base metal by 200%. Despite these enhancements, the corrosion resistance of new samples has decreased by 70%, which can be due to the numerous dislocations in the stress-induced stir zone, creating lattice deformations and causing the breakdown of the passive protective layer. The analysis of fracture surface topography through a Fractography method revealed a specific anaglyph consisting of dimples of various shapes, sizes, and dispersion and further confirmed the tensile test results.

Formation of composite coatings: morphology and composition studies

In this work, composite fluoropolymer-containing coatings were obtained on samples of AMg3 aluminium alloy, MA8 magnesium alloy, and VT1-0 commercially pure titanium treated by plasma electrolytic oxidation (PEO). Superdispersed polytetrafluoroethylene (SPTFE) and a solution of tetrafluoroethylene (TFE) telomers in acetone were applied onto preliminarily formed PEO layers by the spray-coating method. The obtained coatings contained a large amount of crystalline polytetrafluoroethylene embedded in the outer porous layer of the PEO coating and did not have visible defects, which indirectly indicates high protective properties.

Fretting wear mechanism of antifriction coating with selenium on aluminum alloy

The article considers the issues associated with structure and mechanism of destruction of the antifriction coating with selenium on an aluminum alloy during fretting wear in contact with a steel ball. The process of fretting wear of the coupling under the influence of vibrations in heating conditions of up to 200 0C is simulated. The influence of load on the wear resistance index is analyzed. It has been established that an increase in load leads to a decrease in fretting wear of the coating. Testing of an aluminum alloy sample under the same conditions showed that an increase in load leads to an increase in wear resistance. Based on the study, it is proposed to protect the workpiece from vibration to prevent the destruction of the anti-friction coating during logistics operations.

Quantitative analysis of elemental concentrations of aluminum alloys using calibration-free femtosecond laser-ablation spark-induced breakdown spectroscopy

In this work, the calibration-free (CF) methodology combined with femtosecond laser-ablation spark-induced breakdown spectroscopy (fs LA-SIBS) was applied for the quantitative analysis of elements in aluminum alloy. A femtosecond laser (800 nm) operated at a repetition rate of 1 kHz with a pulse width of 35 fs was used as the laser-ablation source, and the plasma emission was enhanced by the spark discharge. Spectra were acquired using a compact fiber spectrometer coupled to a charge-coupled device and recorded at 200–500 nm. The aluminum alloy sample was mounted on a two-dimensional motion platform, and the effect of the sample moving speed on the spectral intensity was investigated. To evaluate the analysis performance of this technique, five standard aluminum alloy samples with certified elemental concentrations were tested. The average estimated electron density from these five transitions was (1.5 ± 0.3) × 1017 cm−3, which was determined by fitting the ion spectrum of Al II (281.62 nm) with Lorentz fitting. The plasma temperature was calculated to be 6300 ± 300 K using Saha–Boltzmann plots under the local thermodynamic equilibrium state. Trace elements with the content of <0.1% were detected by the proposed technique, and the analysis error of Al was <0.3%. This study shows that the CF fs LA-SIBS technique can be employed for quantitative analysis of major, minor, and trace elements in multi-composition alloys.

Study on quasi-in-situ tensile microstructure evolution law of 5052-O aluminum alloy based on EBSD

SHIMADZU AGS-100KN universal testing machine was used to carry out tensile experiments of 2.2%, 5%, 10%, 15%, 20% and 25% of different tensile elongations on 5052-O aluminum alloy. The surface DIC morphology characteristics and the evolution law of the microstructure of samples under different elongation rates were studied by the DIC (digital image correlation) and the EBSD (electron backscatter diffraction). The results show that the tensile strength of the 5052-O aluminum alloy reaches the maximum value of 205.632 MPa and the elongation at failure is 28.8%. When the tensile deformation is 2.2%, there is an obvious slip band at 45° to the direction of the tensile axis. At 10% deformation, the slip band is obviously narrowed, with darker interior color and large deformation. With the gradual increase of the deformation, the proportion of the microstructure recrystallization area and the substructure area decreases, and the proportion of the deformation area increases. The plastic deformation mechanism is mainly the dislocation slip. The low angle grain boundary gradually increases and the high angle grain boundary decreases as the increase of deformation. When the deformation is above 15%, the changing trend of low-angle and high-angle grain boundaries also slows down. During the tensile deformation process, the corresponding KAM (Kernel Average Misorientation) value distribution curve value is constantly moving to the right and expanding. The R-type texture {124}< 211 > always exists, the Brass texture {110}< 112 > and the S-type texture {123}< 634 > keep increasing. • During the quasi-in-situ tensile test of the 5052-O aluminum alloy sample, the change of the sample morphology was continuously recorded by DIC. It can dynamically observe the microstructure changes of the specimen during the tensile process. • EBSD was used to study the evolution of grain orientation, the change of recrystallization region and the statistics of crystallographic orientation difference of specimens under different deformations during tensile deformation. It reveals the stress concentration mechanism in the deformation region and discusses the evolution of texture after tensile deformation. It provides some theoretical basis for the process optimization in industrial production. • Through the analysis of the texture evolution, the R-type texture {124}< 211 > existed during the deformation process. The Brass texture {110}< 112 > and S-type texture {123}< 634 > continued to increase with the tensile deformation increased.

Effect of microarc oxidation on the properties of aluminum alloy samples

Currently, modern manufacturing industries impose special requirements on structural materials such as aluminum, titanium, and their alloys. Various methods are used to improve the physicomechanical and corrosion properties of these materials. One of the promising ways to modify the surface in order to give it multifunctional properties is the treatment of micro-arc oxidation. A distinctive feature of the process is the formation of the oxide coatings on valve metals because of exposure to micro-arc discharges. At the same time, coatings with unique properties are formed. However, the effect of the micro-arc oxidation process on the properties of the base material has been little studied. The purpose of this work is to study the effect of the micro-arc process, implemented in pulsed mode, on the properties of oxide layers, and the base material. Modification of the alloy surface was carried out in the anode mode, with small values of the duration of the anode current pulse. An alkaline electrolyte solution was used as the electrolyte. Studies of the microhardness of the oxide layer, as well as the metal layer from the interface – oxide layer /metal deep into the metal, have shown that micro-arc discharges affect not only the properties of the oxide layer but also structural changes in the thickness of the metal. It is shown that the formed oxide coating is characterized by high microhardness. The oxide coatings obtained at the duration of the anode current pulse of 100 µs – 200 µs are wear-resistant, the coatings do not collapse, and do not wear to the ground under the accepted test conditions.

Effect of aging plus cryogenic treatment on the machinability of 7075 aluminum alloy

This work aims to explore the effect of aging plus cryogenic treatment on the machinability of 7075 aluminum alloy in high speed cutting. First, 7075 aluminum alloy samples are pretreated by T6 and T6I4. Then they are cryogenically treated under −196°Cfor 168 h. After heat and cryogenic treatment, the samples are experimentally cut at high speed. Samples having received only T6 or T6I4 treatment are selected as the control groups. Surface quality and microstructure evolution are analyzed by SEM, EDS, XRD, TEM, and HRTEM means. The results show that the cutting force of 7075 aluminum alloy is significantly smaller than without cryogenic treatment after cryogenic treatment,; the cutting force of T6-state alloy is 1.25 times as much as the T6I4-state alloy. Under the same cutting parameters, cryogenically treated 7075-T6I4 aluminum alloy has a smaller grain size and contains more precipitates in the aluminum matrix, which are η-MgZn2. The precipitated phase size of T6 is about 80 nm, about 2.5 times that of T6I4.After T6 and T6I4-state samples are cryogenically treated, the alloy precipitate size is about the same as-or slightly smaller than-the grain size of the alloy without cryogenic treatment, but the precipitates are denser and discontinuous. After T6 and T6I4 heat treatment, distinctive stacking fault arises in the machined surface. After cryogenic treatment, the stacking fault is greatly improved.

Benchmark Al-Cu Solidification Experiments in Microgravity and on Earth

Predicting macrosegregation and grain structure, including the columnar to equiaxed transition (CET), in alloy solidification is an ongoing challenge. Gravity-driven melt convection and transport of unattached solid grains complicate such efforts. Cylindrical samples of aluminum alloys containing 4, 10, and 18 wt pct copper are solidified from the bottom upwards on Earth and in microgravity conditions aboard the International Space Station. The chosen alloys possess primary solid densities that are greater than, equal to, and less than their melt densities promoting different gravity-driven solid transport phenomena. Significant differences in grain structure are observed between microgravity and terrestrial samples. All microgravity samples are entirely equiaxed, while the terrestrial samples exhibit a CET. The columnar grains near the cooled surface in the terrestrial samples can only be attributed to melt convection. The Al-4 wt pct Cu terrestrial sample shows evidence of grain sedimentation, while the Al-18 wt pct Cu terrestrial sample exhibits the effects of grain floatation. Measurements of eutectic fraction and solute concentration in the samples show inverse segregation due to shrinkage-driven flow in all samples. Terrestrially solidified samples have areas of high solute concentration that are not uniformly distributed over the diameter, indicating the presence of melt convection. The eutectic and macrosegregation measurements generally have good correspondence. Temperature, grain structure, eutectic fraction, and macrosegregation data are presented as benchmark data to validate future modeling efforts. Heat flux boundary conditions on the sample are determined using thermal modeling. Thermal process parameters are calculated for all samples.

Thermal Creep Behavior and Creep Crystallization of Al-Mg-Si Aluminum Alloys.

The experimental temperature is 613.15~763.15 K, and the strain rate is 0.01~10 s-1. The hot compression creep test of the 6082-T6 aluminum alloy sample is carried out by Gleeble-3500 hot compression simulation compressor, and its creep behavior is studied by scanning electron microscope. The results show that the DRX crystal has an irregular shape and that content of the Mg phase, Si phase, and Mn phase in the crystal are the main factors to change the color of DRX crystal. Temperature and strain rate are important factors affecting dynamic recrystallization. Reducing temperature and increasing strain rate will weaken dynamic recrystallization, and DRX critical condition and peak stress (strain) will increase. The constitutive equation of hot creep of 6082 aluminum alloy was established by introducing the work hardening rate-rheological stress curve, and the relationship between DRX critical condition, peak stress (strain) and parameter Z during creep was explored. Based on the Av rami equation, the prediction equation of the DRX volume fraction is established. With the increase of strain, DRX volume fraction is characterized by slow increase, then rapid increase and then slowly increase. In the hot -forming extrusion process of 6082 aluminum alloy, according to the volume fraction prediction equation, the DRX can be reduced, and the internal structure of the material can be optimized by changing the extrusion conditions and particle size.

Application of quantitative analysis for aluminum alloy in femtosecond laser-ablation spark-induced breakdown spectroscopy using one-point and multi-line calibration

To achieve the quantitative elemental analysis of aluminum alloy samples, the one-point and multi-line calibration (OP-MLC) method and femtosecond laser-ablation spark-induced breakdown spectroscopy (fs-LA-SIBS) were combined in this study. An ultrafast Ti: sapphire laser with high single-pulse energy and high repetition–rate operation was used as the laser source to ablate the sample at a 1k Hz pulse repetition rate and achieve re-excitation using spark discharge. Subsequently, an enhanced spectral peak intensity was achieved, which increased the sensitivity and analytical capabilities of laser-induced breakdown spectroscopy (LIBS) technique. Considering only one confirmed sample, the OP-MLC method was used to calculate the concentration ratios of trace elements Mg, Cr, Cu, Mn and Zn in four aluminum alloy samples to the calibration samples by the integral intensity ratio of the elemental characteristic lines between the two samples. The average relative errors with the identified concentrations were 3.99%, 15.13%, 8.76%, 9.30% and 9.64%, respectively. The results showed that the combination of OP-MLC method and fs-LA-SIBS has good accuracy in the quantitative analysis of elements, and has the advantages of simplicity, rapidity and high sensitivity.

Laser-processed antiadhesive bionic combs for handling nanofibers inspired by nanostructures on the legs of cribellate spiders.

Nanofibers are drawing the attention of engineers and scientists because their large surface-to-volume ratio is favorable for applications in medicine, filter technology, textile industry, lithium-air batteries, and optical sensors. However, when transferring nanofibers to a technical product in the form of a random network of fibers, referred to as nonwoven fabric, the stickiness of the freshly produced and thus fragile nanofiber nonwoven remains a problem. This is mainly because nanofibers strongly adhere to any surface because of van der Waals forces. In nature, there are animals that are actually able to efficiently produce, process, and handle nanofibers, namely cribellate spiders. For that, the spiders use the calamistrum, a comb-like structure of modified setae on the metatarsus of the hindmost (fourth) legs, to which the 10-30 nm thick silk nanofibers do not stick due to a special fingerprint-like surface nanostructure. In this work, we present a theoretical model of the interaction of linear nanofibers with a sinusoidally corrugated surface. This model allows for a prediction of the adhesive interaction and, thus, the design of a suitable surface structure to prevent sticking of an artificially nonwoven of nanofibers. According to the theoretical prediction, a technical analogon of the nanoripples was produced by ultrashort pulse laser processing on different technically relevant metal surfaces in the form of so-called laser-induced periodic surface structures (LIPSS). Subsequently, by means of a newly established peel-off test, the adhesion of an electrospun polyamide fiber-based nonwoven was quantified on such LIPSS-covered aluminium alloy, steel, and titanium alloy samples, as well as on polished (flat) control samples as reference and, additionally, on samples with randomly rough surfaces. The latter revealed that the adhesion of electrospun nanofiber nonwoven is significantly lowered on the nanostructured surfaces compared with the polished surfaces.

Wear and microstructure analysis of aluminium based composite using eggshell and rice husk ash as reinforcement

PurposeThe purpose of this paper is to study Al-based green composite. To make composite samples of aluminium alloy (AA3105) with different weight percentages of rice husk ash (RHA) and eggshell (ES) particles as reinforcement, stir casting method was used.Design/methodology/approachSeveral other aspects, including the weight percent of reinforcing agent particles, the applied stress and the sliding speed, were taken into consideration. During the course of the wear test, the sliding distance that was recorded varied from a minimum of 1,000 m all the way up to a maximum of 3,135 m (10, 15, 20, 25 and 30 min). The typical range for normal loads is 8–24 N, and their speed is 1.58 m/s.FindingsWith the AA/ES/RHA composite, the wear rates decreases when the grain size of the reinforcing particles enhanced. Scanning electron microscopy images of worn surfaces show that at low speeds, delaminating and ploughing are the main causes of wear. At high speeds, ploughing is major cause of wear. Composites with better wear-resistant properties can be used in wide range of tribological applications, especially in the automotive industry. It was found that hardness increases at the same time as the weight of the reinforcement increases. Tensile and hardness were maximized at 10% reinforcement mix in Al3105.Originality/valueIn this work, ES and RHA has been used to develop green metal matrix composite to support green revolution as promoted/suggested by United Nations thus reducing the environmental pollution.

Model transfer method based on piecewise direct standardization in laser-induced-breakdown spectroscopy.

A large number of certified samples are usually required to build models in the quantitative analysis of complicated matrices in laser-induced-breakdown spectroscopy (LIBS). Because of differences among instruments, including excitation and collection efficiencies, a quantitative model made on one instrument is difficult to apply directly to other instruments. Each instrument requires a large number of samples to model, which is very labor intensive and will hinder the rapid application of the LIBS technique. To eliminate the differences in spectral data from different instruments and reduce the cost of building new models, a piecewise direct standardization method combined with partial least squares (PLS_PDS) is studied in this work. Two portable LIBS instruments with the same configuration are used to obtain spectral data, one of which is called a master instrument because its calibration model is directly built on a large number of labeled samples, and the other of which is called a slave instrument because its model is obtained from the master instrument. The PLS_PDS method is used to build a transfer function of spectra between the master instrument and slave instrument to reduce the spectral difference between two instruments, and thus one calibration model can adapt to different instruments. Results show that for multiple elemental analyses of aluminium alloy samples, the number of samples required for slave modeling was reduced from 51 to 14 after model transferring by PLS_PDS, and the quantitative performance of the slave instrument was close to that of the master instrument. Therefore, the model transfer method can obviously reduce the sample number of building models for slave instruments, and it will be beneficial to advance the application of LIBS.

Properties of Aluminium Cellular Materials Produced by Powder Metallurgy Using the Foaming Agent TiH2

A considerable attention is paid to the production and monitoring of the properties of metallic cellular structures and the properties of aluminium foams, respectivly. Foam structures can be manufactured in three basic ways (by blowing the external gas into the melt, by melt gasification due to the thermal decomposition of the foaming agent, by the melting of the foamable preform which contains foaming agent particles). The paper addresses to our publication [18] and furthermore focuses on the investigation of mechanical properties of two types of foamed AlSi12 aluminium alloy samples. Samples (150x25x10 mm) were produced by powder metallurgy using a foaming agent TiH2. The characteristics features of the produced foam structures (relative density, porosity, volume fraction of solids, Young's modulus of elasticity) were studied on AlSi12 alloy samples. In addition, the porosity of samples and continuity of their air cells were monitored usign the scanning electron microscope.