Phase Composition Of Alloys Research Articles

Structure and phase composition of tungsten alloys modified by compression plasma flows and high-intense pulsed ion beam impacts

Abstract The results of structure and phase composition change in tungsten after compression plasma flow and high-intensive pulsed ion beams impacts are discussed. The compression plasma flows with the absorbed energy in range 35–70 J/cm2 were used for the sub-surface modification. The preliminary Ti coating deposition on the tungsten surface allowed us to form W-Ti alloys by plasma flows treatment. The layer of the W-Ti alloy consists of solid solutions W(Ti) and β-Ti(W) as well as nitride phase (Ti,W)N. The high-intensive pulsed ion beam impact provides the tungsten carbide W2C formation in the sub-surface layer. When forming the W-Ti alloy the carbon ions implanted into the tungsten take part in the carbo-nitride (Ti,W)(N,C) formation without brittle W2C phase.

Influence of Surfacing Technologies on Structure Formation of High-Temperature Nickel Alloys

The paper presents the results of studying the formation of structure and properties of metals when using additive technologies, such as arc and laser surfacing of highly alloyed nickel alloys. The main problem of nickel-chromium alloys during treatment with highly concentrated energy sources (welding, surfacing, soldering, plasma and laser treatment) consists in low strength and heat resistance after heating to high temperatures and rapid cooling, which is typical for these methods. The maximum high-temperature strength of such alloys is achieved after quenching and subsequent aging resulting in the formation of finely-dispersed γ′- phase precipitates, which inhibit plastic deformation. However, the achieved level of high-temperature strength of nickel alloys is often reduced significantly as a result of thermal effects and unfavorable structural changes during subsequent treatment (welding, surfacing). The paper presents the results of studying the structure, phase composition and properties of EP648 alloy during argon-arc surfacing. A comparison with the EP648 alloy structures obtained by laser surfacing is provided. It was established that argon-arc welding of EP648 alloy in combination with ultrasonic treatment creates an additional effect of increasing phase dispersion, which leads to an increase in hightemperature strength of the alloy.

Tailorable deposition of Sn[sbnd]Ni alloy from a pyrophosphate bath with an adjustable Sn:Ni molar ratio

Tailorable deposition was carried out by varying the Sn:Ni molar ratio of a pyrophosphate bath to adjust the deposition rate as well as the phase composition, morphology and corrosion resistance of the as-deposited SnNi alloy. The nickel content of the resultant SnNi alloy decreases gradually from 50 wt% to 28 wt% when the Sn:Ni molar ratio of electrolytes increases from 0.2 to 2.0 and remains reasonably constant at 31–37 wt% when the ratio is in the range of 0.6–1.8. Codeposition of a reasonable content of Ni with tin refines the crystal grains of the alloy and produces a compact coating. The phase composition of the SnNi alloy deposition changes along with the Sn:Ni molar ratio, and alloys with low nickel content are composed of Ni4Sn, Ni3Sn2 or Ni3Sn4 phases. A single-phase homogeneous intermetallic compound of Ni4Sn appears in alloys containing 31–37 wt% nickel. Compared to pure deposited Sn, the electrochemical measurements reveal that the SnNi alloys containing single-phase Ni4Sn have a smaller corrosion current density, smaller blunt current and larger electrochemical charge transfer resistance in 10% H2SO4 solution, indicating that the nearly equiatomic alloy SnNi exhibits excellent corrosion resistance in sulfuric acid solution.

Projection of phase composition of lowcost titanium alloy welded joints by finite element mathematical modeling method

Projection of phase composition of lowcost titanium alloy welded joints by finite element mathematical modeling method

Characterisation and Performance Optimisation of WC-MC/M(C,N)-Co Hardmetals

WC-MC/M(C,N)-Co hardmetals with 10 wt% Co were prepared in undoped, as well as in either Cr- or V-doped form. The starting formulations contained 5 wt% TiC or 5% (TiC+TiN), the latter with two different TiC/TiN ratios, and 10 wt% (Ta,Nb)C. For each composition, a low-C grade (Ms ≈ 75%) and a high-C grade (Ms ≈ 88%) was adjusted by C or W addition, to end up with 18 different hardmetal formulations, prepared in an industrial process. Model alloys, MC and M(C,N) phases with a composition reflecting the composition of these phases in the hardmetal were prepared, too. A variety of data was collected: binder phase and hard phase compositions of model alloys by wavelength-dispersive electron-probe microanalysis (WDS-EPMA), liquid phase formation temperatures in model alloys with free C and eta by differential thermal analysis (DTA), respectively, thermal conductivities of MC and M(C,N) phases and hardmetals by laser-flash temperature conductivity and heat capacity measurements up to 950 °C, crystallite-size distribution by electron backscatter diffraction EBSD, hardness HV30, Palmqvist-Shetty fracture toughness KIC, Weibull evaluation of the transverse rupture strength (TRS), oxidation resistance in air as well as milling tests on coated hardmetals with Ti(C,N)/Al2O3 and (Ti,Al)N layers.

Prediction of the Phase Composition of High-Entropy Аlloys Based on Cr–Nb–Ti–V–Zr Using the Calphad Method

Based on the CALPHAD method, a description of the Cr–Nb–Ti–V–Zr alloy system was formulated and temperature dependences of changes in the phase composition of high-entropy CrxNbTiVZr alloys (for x = 0.5, 0.75, 1, and 1.25) were calculated.

Investigation of amorphous alloys nanostructure and phase composition formed during integrated and split exposure of deformation and flash lamp annealing

Microstructure and phase composition of the Al85Ni7Fe4La4 amorphous alloy after separate and complex impacts of severe plastic deformation by shift under the pressure (SPD) with P=8 GPa, n=1-3 revolutions and flash lamp annealing (FLA) with the fluence F=10-25 J/cm2 were investigated. By X-ray structural analysis and transmission electronic microscopy (TEM) was shown, that in initially amorphous structure partial multiphase crystallization with formation of amorphousnanocrystalline composite (solid solution of crystalline Alcr and amorphous Alam and Al11La3, Al9(Fe, Ni)2 in aluminum) is developing during the SPD. FLA leads to partial nanocrystallization at F=10 J/cm2 and full crystallization after the FLA at 20-25 J/cm2. Phase transformation and static recrystallization processes are developed along with the crystallization in amorphous structural component at SPD and FLA integrated exposure.

Effect of dual aging treatments on phase transformation and microstructure in a pre-deformed Ti2AlNb-based alloy containing O + β/B2 structures

The effect of dual aging treatment on phase morphology, composition, and microstructure evolution of a pre-deformed Ti2AlNb-based alloy were investigated in this study. The 1040 °C-pre-deformed alloys were dual aged at different temperature in O + β/B2 region followed by 750 °C-aged treatment. The experimental results show that coarse O lath and lamellar O + β/B2 were formed when the aging temperature is lower than 950 °C while globular O appeared when aging temperature is higher than 950 °C. The size and content of the O phase increase and decrease with the aging temperature, respectively. Widmanstätten O + β/B2 laths were obtained after secondary aging treatment at 750 °C when the first aging temperature is higher than 910 °C. Complete lamellar O + β/B2 precipitation and coarse O lath, in particular, were obtained in the 910 °C and 750 °C dual aged alloy with no Widmanstätten O + β/B2 laths appeared. The phase content is closely related to the aging temperature. When the 970 °C-aged alloy put into the secondary aging at 750 °C, coarse O laths which were fragmented or partially spheroidized and globular O during 970 °C-aged process were dissolved and the Widmanstätten O began to precipitate inside.

Hydrogenation properties of nanocrystalline Ti[sbnd]V[sbnd]Mn body-centered-cubic alloys

An effect of Mn content in nanocrystalline TiVMn alloy on hydrogenation properties has been investigated systematically in this work. Ti0.5V1.5-xMnx (x = 0, 0.1, 0.2, 0.3) alloys are synthesized by mechanical alloying method. It has been shown that all alloys need to be activated in order to present the best hydrogenation properties. With increasing Mn content in TiVMn alloys, the maximum hydrogen storage capacity at room temperature firstly increases to reach 3.07 wt% for Ti0.5V1.4Mn0.1 alloy and then gradually decreases. Reversibility of hydriding-dehydriding process improves after chemical modification of TiV alloy. Hydrogen storage properties result from phase composition and structure of alloys. All samples are composed of a major body-centered-cubic (BCC) phase. In Mn-containing materials also a second BCC phase has been detected. Its abundance increases with higher content of Mn in the alloy. Moreover, with increasing Mn content, the lattice parameters of both phases decrease.

Effect of Heat Treatment on the Structure and Phase Composition of a High-Temperature Nickel Alloy Obtained by Laser Cladding

Modes of laser cladding of heat-resistant nickel alloy Inconel 625 are considered. The gas-powder flow is studied and optimized as a function of the flow rate of the protective and transporting gas. The effect of the heat treatment modes on the structure and phase composition of the alloy is analyzed. Amode producing compact samples of the alloy is worked out.

Differential Thermal Analysis of Complex Alloyed Brass

Copper alloys are widely used in mechanical engineering. In the article it is shown that the requirements of consumers to properties of alloys are constantly increasing. Complex alloyed brasses have a high wear resistance and corrosion resistance. The wear resistance is a basic property of an alloy. This characteristic determines the operating life of parts working in the wear conditions. The wear resistance is supported by phase composition of alloy, uniformity of distribution of phase in the structure of alloy, their volume fraction, their morphology and their dimensions. At present time the technology of continuous casting of ingots of alloys Cu59Zn34.6Mn3.5Al2.5Fe0.5Ni0.4, Cu70Zn13Mn7Al5Fe2Si2Pb1, Cu58Zn36Mn2Pb2Si1Al1 and Cu58Zn35Mn3Si1.5Ni1.5Pb1 is developed. However, the need to use new alloys for manufacturing of critical parts requires the development of technology for their production, taking into account the composition of alloy and the features of formation of structure. Therefore, it is necessary to establish well-founded technological parameters of melting and casting of ingots of complex alloyed brass Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2. For determination of temperatures of phase transformations in the structure of alloy, the differential thermal analysis was carried out. Liquidus and solidus temperatures of alloy were determined. The crystallization range of alloy was established. This brass in a solid state undergoes two phase transformations. The temperature of the first phase transformation is 750 oC. The temperature of the second phase transformation is 515 oC. The obtained experimental data make it possible to describe the proposed mechanism of phase transformations in alloy Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2 during crystallization and following cooling.

The Effect of Heating on Phase Composition of the Cr<sub>3</sub>C<sub>2</sub>- Ti System Hard Alloys Fabricated by the Explosive Compaction of Powder Mixtures

The article reports findings on theoretically-calculated data and experimental results obtained with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy methods of the analysis of hard alloys produced by the explosive compaction of the Cr3C2 chromium carbide powders with titanium, first in the original condition and then after heating to 1200 °C. It was established that when heated to 600 °С the phase composition of hard alloys does not change and corresponds to the composition of the original components of the powder mixture. When the heating temperature was increased to 650 °С, new fine powder fractions emerged at the “chromium carbide – titanium” interface. At the temperature of 700 °С two separate diffusion layers emerged and grew in the opposite directions. Due to this growth the source phases in the alloy fully disappeared at 1200 °С and two equilibrium phases were formed.

Effect of Cerium and Lanthanum Additives on the Phase Composition of the Copper-Nickel Alloys

An experimental study of the phase composition for nine samples of the Cu–Ni–Ce–La alloys with different content of components was carried out. The nickel concentration in the experimental samples varies from 3 to 40 wt. %, the sum of cerium and lanthanum concentrations was not exceed 7 wt. %. Alloys samples of the system Cu–Ni–Ce–La were studied using scanning electron microscopy and microprobe analysis, as well as X-ray analysis. Also, Vickers micro hardness was measured on the cross sections of the experimental samples. In this work, the conditions of intermetallic compounds formation in the as-cast samples were studied. The results of the work can be used for the technological processes analysis of copper and copper-based alloys production.

Phase constituent control and correlated properties of titanium aluminide intermetallic alloys through dual-wire arc additive manufacturing

TiAl intermetallic compounds were deposited using in-situ alloying with the dual-wire arc additive manufacturing method, and their material properties were investigated. The compounds were designed with different phase constituents and microstructure, achieved through adjusting the elemental wire feed rates according to atomic ratios of Ti: Al = 65%: 35%, 55%: 45%, and 45%: 55%, respectively. Single α2-Ti3Al and γ-TiAl phases were obtained with compositions of Ti-35%Al and Ti-55%Al, while Ti-45%Al resulted in the phase composed of γ-TiAl and α2-Ti3Al. Additionally, the influence of phase composition and microstructure on mechanical properties and oxidation behaviour of the fabricated materials were studied and analysed. In conclusion, the phase composition of TiAl intermetallic alloys could be readily controlled using the dual-wire WAAM method and acceptable properties could be obtained.

Influence of Obtaining Conditions on Microstructure, Phase Composition and Properties of Eutectic Alloy of WC-W2C System

The influence of the obtaining conditions on microstructure, phase composition and properties of eutectic alloy of the WC-W2C system (relit), which is widely used as a surfacing material to strengthen the wearing parts, was installed. Using scanning electron microscopy, X-ray diffraction and durometric analyzes, it was found that the increase in mechanical properties is satisfactorily correlated with a decrease in the ratio between the number of phases of W2C, WC and WC1−x, the thickness of the phase layers in the grains, and the elongation of the latter.

Сравнительное исследование структуры, фазового состава и механических свойств жаропрочных никелевых сплавов, полученных различными методами

Сравнительное исследование структуры, фазового состава и механических свойств жаропрочных никелевых сплавов, полученных различными методами

Preparation of TiAl15Si15 intermetallic alloy by mechanical alloying and the spark plasma sintering method

ABSTRACTThis work is devoted to the preparation of alloys based on intermetallic compounds in the Ti–Al–Si system by powder metallurgy using mechanical alloying and the spark plasma sintering (SPS) method. The aim was to describe the formation of intermetallic phases during mechanical alloying of TiAl15Si15 (wt-%) alloy and to consolidate the powder prepared by optimised conditions. Phase composition, microstructure and hardness of compacted alloy were determined. Four hours of mechanical alloying is sufficient time for preparation of pure elements free material composed only of intermetallic phases. After consolidation, the TiAl15Si15 alloy has a homogeneous structure composed of silicide (Ti5Si3) in aluminide (TiAl) matrix. The hardness of the material reaches 865 ± 42 HV 5.

The Effect of Oxygen on the Phase Composition and Heat Treatment Behavior of Ti-V Alloys

Titanium and its alloys possess high specific strength, excellent corrosion resistance and good biocompatibility [1] [2]. Since oxygen is an unavoidable impurity in such materials, it has been adopted as an alloying element in the development of low-cost titanium alloys. Therefore, it is important to investigate the role of oxygen in these alloys, especially in β-type alloys. In the present study, the effects of oxygen on the electrical resistivity, Vickers hardness and heat treatment behavior of a Ti-20mass%V alloy which is the lowest concentration for which the fully retained β phase is obtained were assessed. The electrical resistivity and Vickers hardness of solution-treated and quenched specimens increased with increasing oxygen content, due to the dissolution of oxygen into the β phase and solid solution hardening, respectively. Upon isothermal aging at 673 K, the addition of O accelerated a-phase precipitation. The addition of O was found to suppress the appearance of the athermal ω phase in the solution-treated and quenched state.

Microstructures and High Temperature Tensile Properties of As-Aged Mg-6Zn-1Mn-4Sn-(01, 0.5 and 1.0) Y Alloys

The microstructures and high-temperature tensile properties of as-aged Mg-6Zn-1Mn-4Sn-(0.1, 0.5 and 1.0) Y (wt.%, ZMT614-Y) alloys were investigated by optical microscopy (OM), X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-temperature tensile tests. The tensile temperatures were 150 °C, 200 °C, 250 °C and 300 °C, respectively. The results showed that the phase compositions of as-aged alloys were α-Mg, α-Mn, MgZn2, Mg2Sn, and MgSnY phases. The Mg2Sn and MgSnY high-temperature phases inhibited grain growth in the heat treatment and tensile processes. The as-aged ZMT614-0.5Y alloy has the best high-temperature mechanical properties, with yield strength (YS), ultimate tensile strength (UTS), and elongation values of 277 MPa, 305 MPa, and 16.7%, respectively, at 150 °C. As the tensile temperature increased to 300 °C, the YS and UTS decreased to 136 MPa and 150 MPa, and elongation increased to 25.5%. The fracture mechanism changed as the tensile temperatures ranged from 150 °C to 300 °C, from the transgranular fracture type at temperatures of 150 °C and 200 °C, to the transgranular and intergranular mixed-mode fracture type when tensile temperatures increased to 250 °C, to an intergranular fracture mechanism at 300 °C.

Effects of Mo contents on the microstructure, properties and cytocompatibility of the microwave sintered porous Ti-Mo alloys

The porous Ti-Mo alloys were prepared by microwave sintering, and the effects of Mo contents on the pore structure, phase composition, compressive strength, elastic modulus, bending strength, corrosion resistance and cytocompatibility of porous Ti-Mo alloys were investigated. The results show that the porous Ti-Mo alloys are composed of α phase and β phase, and the volume fraction of β phase increases with increasing the Mo contents. The amount of Kirkendall pores distributed over the porous Ti-Mo alloys skeleton increases with increasing the Mo contents, which greatly increases the porosities and pore sizes of the porous Ti-Mo alloys. Correspondingly, all of the compressive strength, elastic modulus and bending strength of the porous Ti-Mo alloys decrease with increasing the Mo contents. The porous Ti-Mo alloys present excellent corrosion resistance in the Hank's solution due to the oxidation film of TiO2, MoO2 and MoO3 naturally formed on the surface, and the Mo contents have no obvious effect on the corrosion resistance. The cell viabilities of the porous Ti-Mo alloys are higher than 94%, indicating the porous Ti-Mo alloys possess favorable cytocompatibility. Moreover, the porous Ti-Mo alloys are beneficial to the spread, proliferation and differentiation of osteoblast-like cells, and the Mo contents have no significant effect on the cytocompatibility of the porous Ti-Mo alloys.