Alloy Target Research Articles

Oblique penetration of ogive-nosed projectile into aluminum alloy targets

To better understand the oblique penetration behavior of ogive-nosed projectile into aluminum alloy targets, penetration experiments with impact velocities ranging from 700m/s to 1100m/s and oblique angles of 0, 10°, 20° and 40° were conducted. The Length to Diameter (L/D) of the projectiles were 3 and 4, respectively. Failure modes of target and penetration trajectory were obtained from penetration experiments. Based on the local interaction theory (LIT) and resistance to penetration in dynamic expansion theory (DET), a model to depict penetration trajectory was developed by taking the effects of free surface and wake separation/reattachment into account. The effects of free surface and wake separation/reattachment on penetration trajectory were analyzed by combining the experimental data and calculated results. The results showed that the calculation results were in good agreement with the corresponding experimental data. Besides, influences of oblique angle, impact velocity, and L/D of projectile on the penetration trajectory were discussed based on the calculation and experimental result. Ranges of increments of attitude angle of projectiles and oblique angle at the impact velocity of 900m/s were 98% to 274% and 10° to 30°, respectively. Similarly, the increments of attitude angle of projectile varied from 205% to 128% as the impact velocity increased from 800m/s to 1000m/s when the oblique angle was 20°. When it come to the influence of L/D of projectile on the penetration trajectory, the increments of attitude angle of projectiles were 178% and 79.5% for the L/D were 3 and 4, respectively. In summary, the penetration trajectory became more stable with the increase of L/D of projectile and decrease of impact velocity and oblique angle.

The microstructure and thermoelectric properties of the Mg2(Sn,Si,Bi) films containing excess metal Mg phase

To avoid the uncontrollable Mg content in deposited films caused by the easy evaporation of Mg in alloy target, the Mg2(Sn,Si,Bi) solid solutions films with a tiny of excess Mg metal phase were prepared using a Mg-Sn-Si-Bi alloy target and a high pure Mg target by magnetron sputtering alternately. The phase components, microstructures as well as the thermoelectric properties were systematically investigated. The excess metal Mg phase with a few micron size uniformly distributes in the Mg2(Sn,Si,Bi) solid solution films and the size of the excess metal Mg phase becomes bigger and bigger and the phase gradually convert a narrow strip shape as Mg target sputtering time increase from 40 to 60 s. It is beneficial to an increase in both Seebeck coefficient and electrical conductivity that a tiny excess metal Mg phase exists in Mg2(Sn,Si) based films. The Mg2(Sn,Si) based films containing tiny excess metal Mg phase with an appropriate size posses the highest absolute value of Seebeck coefficient and appropriate electrical conductivity, resulting in the maximum power factor.

Au3Si4- and Au4Si4: Electronically Equivalent but Different Polarity Superatoms.

A series of AuxSi4- cluster anions (x = 1-4) were generated most abundantly by laser ablation of a Au4Si alloy target. Photoelectron spectroscopy and density functional theory (DFT) calculation of AuxSi4- (x = 1-4) revealed that Au3Si4- can be viewed as an electronically closed superatom and is composed of a Si4 unit whose three adjacent edges of a single facet are bridged by three Au atoms. Such phase-segregated structure is facilitated by aurophilic interaction between the three Au atoms and results in a large permanent dipole moment (4.43 D). DFT calculations on an electronically equivalent superatom Au4Si4 predicted a new structure in which the uncoordinated Si atom of Au3Si4- is bonded by Au+. This Au4Si4 is much more stable than a cubic structure previously reported and has a large HOMO-LUMO gap (1.68 eV) and a small permanent dipole moment (0.41 D).

Thermal Stability, Hardness, and Corrosion Behavior of the Nickel–Ruthenium–Phosphorus Sputtering Coatings

Nickel–ruthenium–phosphorus, Ni–Ru–P, alloy coatings were fabricated by magnetron dual-gun co-sputtering from Ni–P alloy and Ru source targets. The composition variation and related microstructure evolution of the coatings were manipulated by the input power modulation. The as-prepared Ni–Ru–P alloy coatings with a Ru content less than 12.2 at.% are amorphous/nanocrystalline, while that with a high Ru content of 52.7 at.% shows a feature of crystallized Ni, Ru, and Ru2P mixed phases in the as-deposited state. The crystallized phases for high Ru content Ni–Ru–P coatings are stable against annealing process up to 600 °C. By contrast, the amorphous/nanocrystalline Ni–Ru–P thin films withstand a heat-treated temperature up to 475 °C and then transform into Ni(Ru) and NixPy crystallized phases at an annealing temperature over 500 °C. The surface hardness of the Ni–Ru–P films ranges from 7.2 to 12.1 GPa and increases with the Ru content and the annealing temperatures. A highest surface hardness is found for the 550 °C annealed Ni–Ru–P with a high Ru content of 52.7 at.%. The Ecorr values of the heat-treated amorphous/nanocrystalline Ni–Ru–P coatings become more negative, while with a high Ru content over 27.3 at.% the Ni–Ru–P films show more negative Ecorr values after annealing process. The pitting corrosion feature is observed for the amorphous/nanocrystalline Ni–Ru–P coatings when tested in a 3.5M NaCl solution. Severer pitting corrosion is found for the 550 °C annealed Ni–Ru–P coatings. The development of Ni(Ru) and NixPy crystallized phases during annealing is responsible for the degeneration of corrosion resistance.

Modifications of microstructures and mechanical properties of CoCrFeMnNi high entropy alloy films by adding Ti element

The phase evolution, microstructure and mechanical properties of CoCrFeMnNiTix (x = 0, 0.2, 0.4, 0.6, and 0.8 in molar ratio, denoted as Tix hereafter) high entropy alloy films (HEAFs) were studied in this work. The films were prepared by co-sputtering of CoCrFeMnNi alloy and Ti targets. Abundant nanotwins were observed in the Ti0 and Ti0.2 films and the crystalline structures of both films were identified to be a single FCC phase. In Ti0.4 and Ti0.6, the matrix exhibited an amorphous structure, and both the nanocrystalline grains and nanotwins were embedded in the amorphous matrix. With further addition of Ti, the Ti0.8 film transformed to an amorphous structure. As a result, there was a phase transition from a single FCC to an amorphous structure with the increasing Ti content. Furthermore, nanoindentation tests showed that the hardness of the films increased from 6.62 GPa in Ti0 to 8.99 GPa in Ti0.8. Micropillar compression tests showed that the fracture strain decreased from >19.42% (no fracture) to 7.78% with the increasing Ti content. The best mechanical properties in compression were observed in Ti0.4, and the compressive yield and fracture strengths were 2.82 and 4.44 GPa, respectively, with the fracture strain of 12.4%, which was achieved by a balanced amount of nanocrystalline grains in the amorphous matrix.

The ion-pair character of the B[formula omitted] state of CuAg

In order to obtain fundamental insight into the bonding properties of transition metals, the (v′,0) B-X transitions (v′=0-2) of the heteronuclear CuAg dimer are re-investigated by applying non-linear four-wave mixing and laser-induced fluorescence spectroscopy. The CuAg molecules in a molecular beam are produced by laser ablation of a Cu/Ag alloy target. Rotationally resolved spectra of the B-X transition are recorded. The measurements yield accurate molecular constants for four isotopologues and an equilibrium distance re=2.4577±0.0003 Å for the B state. In particular, the B state is identified as an Ω=0+ ion-pair state. The results corroborate the important contribution of the charge-transfer state to the metal–metal bond. The results are in good agreement with the recent calculations at the MRCI level of theory (Alizadeh et al., 2014).

Deposition of Multicomponent AlTiCrMoN Protective Coatings for Metal Cutting Applications

The high potential of the protective coatings for metal machining applications using the physical vapor deposition (PVD) processes is one to be valued, and will accelerate development of the multicomponent coating design and increase the cutting efficiency. In this study, nanostructured AlTiCrMoN coatings in a multilayered structure were fabricated using cathodic-arc deposition (CAD). Controlling the cathode current of both CrMo and AlTi alloy targets in a nitrogen environment, multilayered AlTiN/CrMoN coatings were deposited. The AlTiN and AlTiN/CrMoN multilayered coatings exhibit a face-centered cubic (fcc) structure with columnar morphologies. The highest hardness of 35.6 ± 1.5 GPa was obtained for the AlTiN coating; however, the H3/E*2 and H/E* values were the lowest (0.124 and 0.059, respectively). The multilayered AlTiN/CrMoN coatings possessed higher H3/E*2 and H/E* values of up to 0.157 and 0.071, respectively. The present study investigated the cutting performance of end mills in the milling of SUS316L stainless steel. The cutting performance was evaluated in terms of cutting length and tool wear. Because of high resistance to adhesive and abrasive wear, the end mills coated with multilayered AlTiN/CrMoN showed less flank wear than monolithic AlTiN. The introduction of CrMoN sublayers improved the cutting tool life of AlTiN.

Activation characterization of the Ti-Zr-V getter films deposited by magnetron sputtering

Non-evaporable getter (NEG) thin films provide distributed pumping properties, allowing to achieve ultrahigh vacuum in narrow and conductance limited chambers. It is an ideal solution to deal with the small aperture of vacuum chambers. In this paper, ternary Ti-Zr-V getter film with approximate equal atomic ratio was deposited on oxygen free copper (OFC) substrate by using a developed DC magnetron sputtering system with an alloy target. Microstructural characterization by scanning electron microscopy, atomic force microscopy and energy dispersive spectroscopy (EDX) indicates that the porous getter film exhibit a columnar growth pattern and the grain sizes are very distributed ranging from several up to hundreds of nanometres. The compositions and the corresponding chemical bonding states are analyzed by using in-situ synchrotron radiation X-ray photoelectron spectroscopy after activation for 1 h at different temperatures in ultra-high vacuum. The results indicate that Ti, Zr and V are initially in their high oxidized states, which are gradually reduced in steps to oxides of lower valence states and finally to their metallic states. The reduction of vanadium oxides is more preferable than that of titanium- and zirconium-oxides. Such activation commences at a temperature as low as 150 °C, and can be enhanced by increasing temperature.

Single metal zirconium non-evaporable getter coating

Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. In our earlier work, it has been demonstrated that quaternary Ti–Zr-Hf-V coating deposited from an alloy target in a form of a rod has the lowest desorption yields, the highest sticking probability and sorption capacity. In this paper, a single element Zr target has been explored. This type of target is widely available and produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chambers. Two samples coated with Zr film of dense and columnar structure were analysed and results of the pumping properties and electron stimulated desorption results are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with a quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160 °C. This is close to the activation temperature of Ti–Zr-Hf-V film and lower than that for the widely used ternary Ti–Zr–V film. Single metal Zr coatings demonstrated that it could be a more efficient and inexpensive way of producing the NEG-coated vacuum chambers.

High-quality sputter-grown layered chalcogenide films for phase change memory applications and beyond

This paper summarizes recent progress on thin film growth of chalcogenides by sputtering. The materials discussed include Sb–Te, Bi–Te, Ge–Te, and their superlattices, materials that are technologically important particularly for non-volatile phase change memory. In this work, the sputter-growth behavior of high-quality layered chalcogenide films is discussed. Sputtering is one of the most commonly used thin-film growth techniques in the semiconductor industry, however, the complex interrelationship between growth parameters can lead to difficulty in fabricating high-quality films although the deposition method itself is relatively simple. Here, we successfully demonstrate the fabrication of highly-oriented layered chalcogenide materials by sputtering. The selection of the appropriate sputtering target is important. In particular, it was found that a Te-rich Sb–Te alloy target such as Sb33Te67 is necessary in order to obtain a stoichiometric Sb2Te3 film. Moreover, the growth temperature is also a key factor in obtaining a highly-oriented film, namely the ideal growth temperature for an Sb2Te3 film is between 230 °C and 250 °C after the growth of an amorphous seed layer at room temperature. Furthermore, it was found that this technique is also useful to grow films epitaxially on Al2O3 or Si(111) substrates even though there are some misoriented grains as well as twins present. Finally, we demonstrate the growth of highly-oriented Sb2Te3 films on a flexible substrate. The versatility of sputtering will become technologically more and more important for the various applications represented by phase change memory.

A Hydrogen-Deficient Nickel-Cobalt Double Hydroxide for Photocatalytic Overall Water Splitting.

Developing highly efficient and low-cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a nonstoichiometric nickel-cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble-metal co-catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so-called L-NiCo nanosheets with a nonstoichiometric composition and O2- /Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2- and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h-1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm.

A Hydrogen‐Deficient Nickel–Cobalt Double Hydroxide for Photocatalytic Overall Water Splitting

AbstractDeveloping highly efficient and low‐cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a nonstoichiometric nickel–cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble‐metal co‐catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so‐called L‐NiCo nanosheets with a nonstoichiometric composition and O2−/Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2− and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h−1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm.

Heteroepitaxial growth and microwave plasma annealing of DC reactive sputtering deposited TiZrN film on Si (100)

Epitaxial TiZrN films were successfully grown on Si (100) substrates at high temperature by using DC magnetron reactive sputtering with a Ti0.68Zr0.32 alloy target. Annealing of a grown TiZrN/Si specimen was performed by applying microwave plasma with a gas mixture of N2 and H2 to improve the film quality. The X-ray rocking curve (XRC) width of (200)TiZrN reflection can reach a minimum value of 1.18°. The heteroepitaxial relationship of TiZrN with Si is {001}TiZrN//{001}Si and <110>TiZrN//<110>Si. The (200)TiZrN XRC width of a 20 nm-thick TiZrN film reduces from 1.99° to 0.85° by microwave plasma annealing. As a result of the improvement of the film quality, the annealed film exhibits a much lower resistivity (28 μΩ‧cm) than that of the as-deposited one (44 μΩ‧cm). The surface morphologies of the TiZrN films are smooth with the surface roughness in the range of 1–2 nm.

The Effect of Phase Transformations on the Interaction of Aluminum Alloys at Speeds above 9 km/s

The penetration of an aluminum jet into an aluminum alloy target with a speed of 8–11 km/s is investigated. An analysis of the kinetics and parameters of introduction, and the condition of the surface of the cavity after penetration suggests that the hydrodynamic nature of penetration is violated at speeds of more than 9 km/s because of fusion of interacting metals. The results of the study are intended to develop screen protection for spacecraft from the most dangerous fragments of space debris.

Phase transitions effect on interaction of aluminum alloys at velocities exceeding 9 km/s

The authors investigate aluminum shaped charge jet (SCJ) penetration into an aluminum alloy target at 8–11 km/s velocities. The analysis of kinetics, penetration parameters and structures of cavern surfaces formed after the penetration show that at velocities exceeding 9–11 km/s, the hydrodynamic character of the penetration changes due to the melting of the interacting materials. When during the penetration process SCJ velocity exceed 9 km/s, porous layer of aluminum nanospheres with 20–100 nm in diameter form in the penetration region. The results obtained are appropriate for developing spacecraft shield protections against most dangerous space fragments.

Exploration and optimization of ZrCo(Ti) type film for high hydrogen density and thermal stability of the hydride

Tritium target is of crucial importance in relation to the development of neutron generator apparatus. However, the prevalent Ti target is now suffering from the intricate procedures for activation, limited tritium content at room temperature (RT) and poor ability to fix the helium. Herein, a succession of new type ZrCo(Ti) alloy targets were designed and fabricated by magnetron sputtering. Firstly, the influence of technological parameters (types of substrate, sputtering temperatures, sputtering time and annealing temperatures) on the assemblage and also the hydrogen storage properties of the ZrCo films were systemically studied. The results show that high sputtering temperature is benefit to acquiring high crystallinity of ZrCo films, but the substrates seem to have no significant effect on that. The thickness and grain size of ZrCo film are both positively related to the sputtering time. However, the hydrogen uptake capacities (0.14 wt%~0.79 wt%) for all the prepared ZrCo films are relatively low. After that, the composition and microstructure of the ZrCo films were further regulated and optimized. On the one hand, Zr1-xTixCo films were constructed by introduction of Ti element, achieving a higher hydrogen absorption capacity (~0.7 wt%), but with weak thermal stability in the subsequent hydrogen desorption process (~80% of hydrogen escaped at 500 °C). On the other hand, the surface of the ZrCo film was modified by a thin layer of Ti, forming a serious of double-layer ZrCo/Ti films. The ZrCo/Ti composite films not only achieve extremely high hydrogen storage capacity (1.85 wt%), but also maintain strong thermal stability (only 15.7% of hydrogen escaped at 500 °C). These findings related to the ZrCo(Ti) films in this paper provide crucial reference for the development of tritiated ZrCo film targets, and spark inspiration even for the design of other new-type tritiated film target.

Microstructures, Mechanical Behavior, and Radiation Damage of (Tivcr)X-(Taw)1-X Binary System High-Entropy Alloy Films

The (TiVCr)x-(TaW)1-x binary system thin films were deposited by a magnetron sputtering system with two intermediate alloy targets. The elemental composition were adjusted by tuning the currents of the two targets, and the value of x in the (TiVCr)x-(TaW)1-x binary system changes from 25 to 90 with the current changes. The surface morphology, roughness, element composition and phase structure of the coatings were studied. With increasing the value of x, the film changes from body-centered-cubic (BCC) to BCC + amorphous structures, and the surface morphology and roughness also show a certain correlation with the phase-structure transition. The research focuses on the mechanical properties and radiation response of the film. The nanoindentation method is used to analyze the hardness and modulus of the material, and the wear resistance of the material is analyzed through reciprocating abrasion experiments. The influence of the 70Kev He+ ions implantation on the structure and microstructure was investigated. The results show that at x=0.51, the film exhibits the best mechanical properties under the action of various strengthening mechanisms. On the other hand, forming a BCC polycrystalline structure and an amorphous mixed structure can improve the radiation resistance of the material.

Microstructure and Mechanical Properties of ZrCuSiN Coatings Deposited by a Single Alloy Target

Recently, research has been conducted on nanocomposite thin films containing new additive elements in ZrN. In this paper, a method for depositing ZrCuSiN nanocomposite coatings using a ZrCuSi single target is presented. The ZrCuSi target that was used to easily deposit a ZrCuSiN coating in a mixed gas atmosphere (Ar + N2) was produced by a simple arc melting method (casting process). The effect of the nitrogen content was investigated by depositing a ZrCuSiN coating using alloy targets at various nitrogen gas flow rates (2, 4, 6, and 8 sccm). X-ray diffraction analysis of the ZrCuSiN coatings revealed a ZrN structure with a preferable orientation (200). As the nitrogen flow rate increased, the formation of o-Zr3N4 was dominant in the ZrN formation. A nitrogen gas flow rate of 4 sccm produced a coating with optimal ZrN and a-Si3N4 coordination and maximum hardness (41 GPa). Reciprocal friction tests of all coatings and uncoated carburized SCM415 steel in a 5W30 lubrication atmosphere demonstrated that the 4 sccm coating had the lowest friction coefficient (0.002). Therefore, our method has the potential to be an alternative surface coating technique for materials used in automotive engine parts and various other wear protection applications.

Effect of target material on neutron output and sputtering yield of D-D neutron tube

The application of D-D neutron tube is increasingly widespread. The replacement of the original pure titanium target with an alloy target can effectively improve the defects such as embrittled and not flexible of titanium after hydrogen absorption. In this paper, a titanium film was prepared by magnetron sputtering and characterized by scanning electron microscope (SEM). The prepared titanium target was used to assemble D-D neutron tube. The actual operation of the neutron tube was carried out, and the neutron yield was measured with the 3He neutron monitor. The experimental results are in good agreement with the calculation results by SRIM. Subsequently, the neutron output and target sputtering yield of the D-D neutron tube with alloy targets were calculated by SRIM, and the atomic ratios of scandium-titanium, molybdenum-titanium, niobium-titanium alloy were 0.2, 0.4, 0.6, 0.8, and 1.0. The results show that the neutron yield is relatively high and the sputtering yield is low when the scandium-titanium alloy with atomic ratio of 0.4 is chosen for target material.

Anomalous X-ray scattering study on oxidized TbxDy1-xFe2-y thin films: Influence of thermal annealing on the oxide composition

Thin films of the ternary compound TbxDy1-xFe2-y were prepared by DC magnetron sputtering from a TbDyFe alloy target with the composition same as Terfenol-D alloy (Tb0.32Dy0.68Fe1.92) onto 400 °C Si (001) substrates. The influence of post annealing temperature at 550 °C, 700 °C or 850 °C for 6 h are studied systematically on a series of TbxDy1-xFe2-y samples. However, the annealing process leads to the incorporation of oxygen impurity into the thin film. To understand the effects of annealing temperature on the microstructural and crystalline degree of oxidation of RFe2 thin film, different characterisation techniques such as anomalous X-ray scattering and electron probe micro-analyzer were performed. These measurements show that Fe clusters phase gets segregated from the bulk matrix during annealing at 550 °C and 850 °C but do not segregate while annealing at 700 °C. In this work, we present an anomalous X-ray diffraction measurement on TbxDy1-xFe2-y to determine the composition ratio of rare earth oxides in thin film and compositional analysis.