Course Of Heat Treatment Research Articles

Evolution of the Structure and Physical Properties of the Nanocrystalline Soft Magnetic Alloy

The structure and physical properties of the Fe72.5Cu1Nb2Mo1.5Si14B9 nanocrystalline alloy have been studied both in terms of dynamics, using thermomagnetic analysis and statics, using specimens subjected to a complete course of heat treatment at the specified annealing temperature. In the course of nanocrystallization, there was a peak detected on the curve of permeability, that peak appeared several minutes later than the heat production peak. The permeability peak occurrence can be related to the formation of a sufficiently large amount of the crystalline ferromagnetic phase α-FeSi followed by saturating it with silicon due to diffusion.

Analysis of a failed rocker arm shaft of a passenger car engine

This paper investigates the failure of a rocker arm shaft of a passenger car. The shaft failed by brittle fracture across one of the four holes supporting the shaft into the cylinder head. The running distance of the engine just before failure was 40,626km. Visual examinations of etched sections of the failed shaft and a new one revealed four distinct zones of darker etching appearance. These zones correspond to the four locations where the rocker arms fit the shaft.Microscopic observations of the failed shaft revealed that the four dark-etching areas are surface hardened zones of martensitic microstructure. Furthermore, scanning the microstructure along the failed shaft showed that the heat treatment was so mistakenly extended by excessive heating so that the structure of the shaft near the supporting holes contains considerable content of martensite phase. This conclusion has been confirmed by the results of hardness measurements along the surface of the shaft.Microscopic investigations of the failed shaft revealed the presence of microcracks close to the supporting holes. These cracks may have been induced in the shaft by the non-uniform cooling during quenching in the course of heat treatment, or may be nucleated by repeated loading during service. This premature failure has occurred by the rapid crack propagation because of the lower fracture toughness of the martensite.

Surface Segregation of Fe in Pt–Fe Alloy Nanoparticles: Its Precedence and Effect on the Ordered‐Phase Evolution during Thermal Annealing

AbstractThe front cover artwork for Issue 22/2015 is provided by the Microscopy of Nanoscale Materials Research Group at McMaster University, Canada. The image depicts the marriage between in situ heating and advanced electron microscopy techniques that enabled this research team to track structural, compositional, and configurational evolution of the same alloy nanoparticle over the course of heat treatment. See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201500380.

Correlation of Enhanced Strength and Internal Structure for Heat‐Treated Submicron Stöber Silica Particles

The Stöber–Fink–Bohn (SFB) method allows the synthesis of spherical silica particles over a wide size range. Owing to the complex formation mechanism, the internal structure and related mechanical properties are not well understood. Within this account, the internal structure of synthesized SFB particles is changed systematically by heat treatments. Characterization by colloid titration, infrared spectroscopy, and solid‐state nuclear magnetic resonance spectroscopy and the assessment of mechanical properties for single particles by in situ micromanipulation shed light on structure–property relations. Over the course of heat treatment, SFB particles become denser and owing to condensation of internal hydroxyl groups, the cross‐linking of the silica network is enhanced. The observed chemical and structural changes are reflected by the mechanical properties of the particles: starting from a low Young's modulus and hardness, clearly below the bulk properties of fused silica, both values are increasing over the course of the thermal treatment. Hardness for fused silica is approached after a treatment at 800 °C and exceeded after a treatment at 1000 °C. Young's modulus approaches the bulk value. Furthermore, a significant plasticity is found: the sustained deformations are extremely high, and thus silica spheres with enhanced strength have been obtained by the thermal treatment.

Microstructure evolution of Al–Ti liquid–solid interface

Al–Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al–Ti DRZ were investigated. The result shows that the DRZ, the mixture of TiAl3 and Al, grows layer by layer along their chemical equilibrium zone. In the course, the growth interface moves toward the aluminum side. TiAl3 is the only new phase which forms earliest in the course of heat-treatment. The growth mechanism of the DRZ changes after the phase transition of titanium. Before the phase transition of titanium, the growth of the DRZ is controlled by the dissolution speed of the titanium to the molten aluminum, while after the phase transition of titanium, the growth is controlled by the chemical reaction speed of Al and Ti atoms, and consequently, its growth rate is greatly increased.

A New Method to Examine the Annealing of Two Alloying Elements of 3004-Grade Cast Aluminum by Resistivity and Thermoelectric Power

Simultaneous measurement of electric resistance and thermopower the concentration of manganese and magnesium in the solid solution were determined by using the Matthiessen and Nordheim-Gorter relationships, in case of homogenized continuously cast AlMn1Mg3 alloy. It can be stated that the quantity of magnesium changes only in a small extent in the course of heat treatment while the manganese precipitates from the oversaturated structure between 400°C and 600°C then it dissolves again over 600°C.

Complex Study of H-Induced Structural Rearrangements in FeZr Glasses

Microstructural changes and relaxation processes were examined in Fe-Zr based rapidly solidified samples. These phenomena occur far below crystallization temperature in the course of heat treatment, or even at room temperature, induced by absorbed hydrogen.

The effect of a sauna on blood oxygen transport and the prooxidant-antioxidant balance in untrained subjects

The effect of sauna on blood oxygen transport and the prooxidant-antioxidant state was studied in 18- to 22-year-old men. The course of heat treatment was performed once a week for five months, i.e., twenty procedures in total. A sauna procedure consisted of two exposures for 5 and 10 min at a temperature of 85–90°C and humidity of 10–15%. In young men, dry-air bath exposure resulted in respiratory alkalosis, increased pO2, and a decreased affinity of hemoglobin to oxygen in the venous blood, which increased the transportation of O2 to tissues. A single sauna procedure was associated with the development of oxidative stress, which was expressed as an enhancement of free radical processes and a decrease in antioxidant defense. Oxidative stress intensity decreased after the course of heat treatment. An elevation of nitric oxide formation could modify oxygen-dependent processes in the body.

Time of isothermal holding in the course of in-air heat treatment of soft magnetic Fe-based amorphous alloys and their magnetic properties

On the example of soft magnetic Fe81B13Si4C2 and Fe77Ni1Si9B13 amorphous alloys, the relation between the level of magnetic properties and duration of isothermal holding in the course of heat treatment in air has been studied. The optimum temperature-dependent time τ of isothermal holding has been shown to be related to the volume fraction of domains (Vorth) with orthogonal magnetization in the initial (quenched) ribbon by equation Vorth = ττ1/3. A temperature dependence of the proportionality coefficient α, which determines the degree of diffusion-process activity, has been determined. The results obtained allow us to substantially simplify the choice of optimum conditions of atmospheric heat treatment of soft magnetic Fe-based amorphous ribbons.

Effects of Sericite Clay Coating on Controlling the Oxides Scale Formation in the Course of Heat Treatment of 13Cr-Stainless Steel

Effects of Sericite Clay Coating on Controlling the Oxides Scale Formation in the Course of Heat Treatment of 13Cr-Stainless Steel

Conditions of structure formation in sparingly alloyed steels intended for service under enhanced wear

A new armor lining steel 100Kh3G2MTR is fabricated and investigated. Different regimes of heat treatment of the steel are studied for the purpose of achieving optimal characteristics of abrasive and shock-abrasive resistance in combination with enhanced surface hardness with satisfactory strength and impact toughness of the metallic matrix. Astructural analysis is performed and the mechanism of phase transformations in the surface layer in the course of heat treatment and in service is described.

Mössbauer investigation of temperature transformations in bacterial ferrihydrite

Ferrihydrite nanoparticles formed as a result of the microorganism activity have been studied using Mossbauer spectroscopy, X-ray powder diffraction analysis, and X-ray fluorescence analysis. Three positions of trivalent iron with nonoverlapping ranges of quadrupole splittings have been revealed in bacterial ferrihydrite: QS{Fe3+(1)} = 0.49–0.83 mm/s, QS{Fe3+(2)} = 0.84–1.10 mm/s, and QS{Fe3+(3)} = 1.25–1.73 mm/s. It has been experimentally demonstrated that the Fe3+(3) positions are the centers of nucleation of the hematite phase in the course of heat treatment.

Effect of Heat Treatment on Microstructure and Mechanical Properties of Semi-Solid Formed Magnesium Alloy AZ91D

The semi-solid slurry of AZ91D magnesium alloy was prepared by twin-screw stirring mixer, the microstructure and mechanical properties of semi-solid formed magnesium alloy AZ91D produced by rheo-diecasting and conventional liquid die casting were investigated, respectively. The strengthen mechanism of the semi-solid formed magnesium alloy after heat treatment was analysed by EDS. The results show that the mechanical properties of semi-solid formed magnesium alloy can be enhanced markedly by T4 and T6 heat treatment, owing to decrease of the porosity and less segregation in casting, brittle eutectic compounds dissolves gradually into α-Mg matrix, and the primary phase α-Mg decomposes in the course of heat treatment. In as-cast state, the tensile strength, elongation and hardness of semi-solid formed magnesium alloy AZ91D are 222MPa, 2.3% and 74 HBS, respectively. In T4 heat treatment state, the tensile strength and elongation are increased by 13% and 210%, and in T6 heat treatment state, the tensile strength and hardness are increased by 11% and 16%. The mechanical properties of castings formed by conventional liquid die casting are deteriorated distinctly after T6 heat treatment due to its porosity and crack defects.

Research of Characteristics of Ni-W-P Nanocomposites Containing CeO<sub>2</sub> and SiO<sub>2</sub> Particles

Ni-W-P-CeO2-SiO2 nanocomposites were pulse electrodeposited from the bath containing suspension of nano-sized CeO2 and SiO2 particles. The influence of heat treatment temperature on the structures and properties were studied. The phase structures, surface morphologies, microhardness and oxidation behavior were evaluated by XRD, SEM, microhardness and oxidation weight gain test. Additionally, the sequence of phase transformation of the nanocomposites was found to be as follows: amorphous phase→intermediate metastable→stable alloy phase. Nano-particles co-deposited into Ni-W-P alloy can inhabit the grains growth, increase microhadness and high temperature oxidation resistance during the course of heat treatment.

Adatgyűjtés, adatelemzés hőkezelési folyamat modellezéséhez

We have been looking for the possibility to build a computer model of costly gas utilization in the course of heat treatment of canned meat. This was necessary for us, as the first part of our long-term research, to be able to accomplish minimized costs by synchro-nizing heat treatment processes running side by side and by production programming to define completion time of the cans. First, because of our multiple data (paper based, text file, image file, Excel file), we have arranged them under a common user interface, while defining the best one from the data with different precision appearing in several sources. Based on the accurate data we did correlation and regression analysis to define the data influencing the gas consumption and to see whether our present data was enough to develop a model. Since the furnace has to ensure the steam supply of the heat treatment equipment and the heating of the buildings too, we defined the gas consumption of the furnace which is dependent on the environmental temperature.

Comparative tribological study of air plasma sprayed WC–12%Co coating versus conventional hard chromium electrodeposit

In this work, the properties of air plasma sprayed WC–12%Co coating before and after heat treatment were compared with the properties of the hard chromium electrodeposit. WC–12%Co coatings were heat treated at 650, 900 and 1150 °C for 1 h in an argon atmosphere. XRD patterns confirmed the formation of an amorphous phase in the as-sprayed coating. This amorphous phase gradually transformed to η-carbides in the course of heat treatment of the coating. This transformation was confirmed by the XRD analysis of the coatings heat treated above 900 °C. Pin-on-disc wear test results showed that WC–12%Co coatings had a significantly better tribological performance as compared with that of the hard chromium electrodeposits. The results also indicated that heat treatment of the WC–12%Co coatings at 900 °C gave the highest wear resistance among the coatings, which was due to the formation of hard η-carbides at this temperature.

Hőkezelési folyamat modellezési adatainak előkészítése, elemzése húskonzerv-gyártás gázfogyasztásának optimálásához

We have been looking for the possibility to build a computer model of costly gas utilization in the course of heat treatment of canned meat. This was necessary for us, as the first part of our long-term research, to be able to accomplish minimized costs by synchronizing heat treatment processes running side by side and by production programming to define completion time of the cans. First, because of our multiple data (paper based, text file, image file, Excel file), we have arranged them under a common user interface, while defining the best one from the data with different precision appearing in several sources. Based on the accurate data we did correlation and regression analysis to define the data influencing the gas consumption and to see whether our present data was enough to develop a model. Since the furnace has to ensure the steam supply of the heat treatment equipment and the heating of the buildings too, we defined the gas consumption of the furnace which is dependent on the environmental temperature.

Liquid–liquid phase separation in sodium borosilicate glass: Ordering phenomena in particle arrangement

A structure of 13.9Na 2O · 36.0B 2O 3 · 50.1SiO 2 glass heat-treated at 610 °C for 5 h (glass G1) and 10 h (glass G2) was studied by stereological method on the basis of electron microscopy data obtained from plane sections of samples. It has been found that liquid phase separation in the course of heat treatment leads to formation of spherical particles with the volume fractions 0.047 (G1) and 0.065 (G2). It is argued that the stage of growth takes place in the glass G1 and the Ostwald ripening stage occurs in the glass G2. The analyses of pair correlation functions of particle traces on a secant plane indicate elements of ordering in mutual arrangement of particles for the both glasses G1 and G2. This conclusion is confirmed by results of numerical simulation. The experimental data on the pair correlation functions are in agreement with the results of calculations presented in the literature. It is noted that the ordering elements in mutual arrangement of particles play a key role in light scattering and other physical properties of material.

On the nature of the second-order optical nonlinearity of nanoinhomogeneous glasses in the Li2O-Nb2O5-SiO2 system

The submicroscopic structure of lithium niobium silicate glasses of the compositions 2xLiNbO3 · (1 − x)(Li2O · 2SiO2) (x = 0.40, 0.45, 0.50) and 30Li2O · 25Nb2O5 · 45SiO2 in the initial state and after heat treatment for different times at temperatures in the vicinity of the glass transition point T g are investigated using X-ray powder diffraction, small-angle neutron scattering (SANS), synchrotron small-angle X-ray scattering (SAXS), and electron microscopy. A nanostructure with inhomogeneities ∼40 A in size is formed in glasses at the initial stages of phase separation at temperatures in the range 600–670°C. This structure is responsible for the appearance of the second-order optical nonlinearity. The SANS, SAXS, and electron microscopic data on the inhomogeneity size are in good agreement with each other. According to the X-ray diffraction, SANS, and SAXS data, the ordering of the glass structure and the difference between the density of inhomogeneities and the density of the matrix increase in the course of heat treatment. At the initial stage of amorphous phase separation, the glass decomposes into regions enriched in SiO2 and regions with an increased content of lithium and niobium. An increase in the temperature or time of heat treatment results in the precipitation of LiNbO3 ferroelectric crystals. The results obtained allow us, for the first time, to make the inference that nanoscale changes in the glass structure lead to considerable changes (by one order of magnitude and more) in the quadratic optical nonlinearity, which can be controlled by heat treatment. The origin of the second-order optical nonlinearity is associated with both the nanosized modulations of the polarizability due to the inhomogeneous glass structure and the polarity of structural nanoinhomogeneities from which the LiNbO3 phase precipitates at the later stages of phase separation.

Evolution of the properties of sol-gel derived hybrid organic-inorganic xerogels and coatings in the course of heat treatment

The sol-gel systems and thin-layer insulating coatings prepared from these systems are investigated by a number of modern experimental techniques, such as IR spectroscopy, differential thermal and X-ray powder diffraction analyses, and methods of extraction and reduction of carbon. These coating are successfully used as electrical insulation for winding wires and other metal surfaces. The glass-ceramic coatings on nickel plates are prepared from the sol-gel system based on tetraethoxysilane (TEOS); potassium, strontium, lead, and cobalt nitrates; low-and high-molecular polyols; and a finely dispersed filler Cr2O3. It is revealed that the structure and composition of the prepared silicate and hybrid xerogels and coatings are changed in the course of their heat treatment and upon introduction of organic modifiers (polyols) into the sols.