Papers by Keyword: Intermetallic Alloy

Abstract: The present work deals with the synthesis and characterization of Al-Cu-SiC-Al₂O₃ hybrid metal matrix composite with varying percentage of Al₂O₃. The synthesized hybrid composite samples were conventionally sintered at two different sintering temperatures i.e. 500°C and 600°C for 1 hr each. SEM investigation predicts the uniform distribution of reinforcing particles. The SEM and XRD results of the sintered composites revealed the presence of a new intermetallic alloy CuAl₂ phase along with Al and SiC phases. It is observed that the density and hardness of Al-Cu-SiC-Al₂O₃ hybrid composite increases with increase in wt % of Al₂O₃ and sintering temperature.

Abstract: Already, there are several processes to produce intermetalic alloy parts from powder , ex. metal injection molding (MIM) or additive manufacturing (AM). For these processes, pre-alloyed powder made by gas atomized powder is used because of their quality. As other way, intermetallic alloy can be produced combustion reaction process. On this process, ingredient metal powders are mixed and reacted by combustion. However, powders are fused by reaction heat, and they are difficult to keep the powder condition. There for, we are developed the process to produce intermetallic alloy precursor by slow combustion reaction. On this process, temperature of mixed powders increases slower than 0.2K/sec. while the combustion reaction, and powders are reacted without fusing. Using this process, TiAl presursor is synthesized. Relation of reacting condition and quality of the precursor is evaluated, and researched the practical usage of this precurser.

Abstract: Intermetallic alloy of tungsten silicide (WSi₂-W₅Si₃) was synthesized by self-propagating high temperature synthesis (SHS) from the reactant of tungsten oxide (WO₃) and silicon lump (Si) using magnesium (Mg) as fuel. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the possible reacting species. The as-SHS products were characterized by X-ray diffraction (XRD) technique. The magnesiothermic reaction process successfully synthesized dense of WSi₂-W₅Si₃ intermetallic alloy. According to the experimental results, it can be proposed that the reaction also promotes the phase separation between alloy and oxide slag of the product.

Abstract: Results of an analysis of effect of wearing type on surface structural changes of a Ni₃Al intermetallic alloy, are shown in the present paper. A microstructure evaluation was carried out by Quanta 3D FEG field emission gun scanning electron microscope (FEG SEM) equipped with an integrated EDS/WDS/EBSD system. The Ni₃Al-based intermetallic alloy with an addition of boron, zirconium and chromium was examined. The investigated material had γ’ single-phase, ordered solid solution structure with 20 μm grain size. An electron backscatter diffraction (EBSD) method was applied to visualize surface structural changes upon an abrasive, a cavitational and a tribological wearing of the material.An observation of surface layer after the abrasive wear was carried out on samples examined in loose abradant by T-07 tester and according to GOST 23.2008-79 norm. An analysis of cavitational wear on changes in the near surface area of Ni₃Al-based alloy was performed on an impact-jet stand. Observed structural changes were described based on results of the SEM/EBSD complex structural examination and hardness measurements. It was found, that the EBSD is an effective and sensitive method that allows estimating surface strain introduced during analyzed wearing types.

Abstract: The aim of this paper was to determine the resistance to high-temperature corrosion in atmosphere of air for alloy Fe-40Al-5Cr-0.2Ti-0.2B. Corrosion tests were conducted in temperatures from 600 to 900°C in time from 2 to 64 hours. Conducted tests have shown a slight increase of weight of samples in periods of time which followed. Increase of weight is connected with corrosion products in the form of passive oxides which form on the surface of the alloy. Kinetics of corrosion processes has parabolic course in tested temperature range which proves the formation of passive layers of corrosion products on the surface of samples. Heat resistance of the alloy on intermetallic phase matrix FeAl brings about potential possibilities to apply this alloy as a material meant for work in elevated and high temperatures in the environment which includes oxygen.

Abstract: Presented article describes results of studies concerning on influence of forming processes on alloy characteristics based on the FeAl intermetallic phase matrix. Microstructure of the alloy was evaluated with optical microscope after crystallization and forming process. Measures of hardness were taken using Vickers method. Static tensile test was used to set limitation of malleability and ultimate tensile strength. Crack surface after static tensile test was observed using scanning electron microscope.

Abstract: The effect of Ti addition on phase equilibria among Ni (A1), Ni3Al (L12) and Ni3V (D022) phases at 950 °C was investigated through TEM/EDS analysis on heat-treated alloys. The three-phase coexisting region of A1 + L12 + D022 was found to exist around the composition of Ni-4Al-19V (at. %) in the Ni-Al-V ternary system. With addition of Ti to the ternary system the three-phase coexisting region was shifted to the Ni-rich side. Ti partitioned most into the L12 phase and least into the A1 phase. These results suggest that the addition of Ti stabilizes the L12 and D022 phases against A1 phase, and raises the temperature of eutectoid reaction in the Ni3Al-Ni3V pseudo-binary system: A1 → L12 + D022.

Abstract: A three-step combined analytical and numerical approach to thermal modelling of a two-heater power-down furnace for controlled directional solidification of an intermetallic alloy is proposed. An analytical sensitivity analysis of the thermal model is carried out to show the effect of adiabatic zone length, and both hot-zone and cold-zone heater temperatures, on the initial thermal gradient in the sample and on the length of melt in the adiabatic zone. The subsequent axisymmetric front tracking method (FTM) simulations of directional solidification of a binary intermetallic Ti-46at.%Al alloy show that temperature gradient in the melt declines and velocity of the solid-liquid front increases with time, thus promoting good conditions for a columnar to equiaxed transition. The proposed analytical calculations combined with full-scale numerical FTM simulations provide a convenient and predictive optimization tool for the two-heater power-down furnace design and growth conditions for the future microgravity experiments.

Abstract: The Low Temperature Heat Capacity of the layered structure Nd3Ni13-xCoxB2 (x = 0, 1, 3, 6, 8, 11 and 13) solid solutions has been measured from 350 mK to 300 K. For high Co content (x ≥ 8), a hyperfine contribution has been explained as due to hyperfine fields of 112.4 kG for Co and 3.68 MG for Nd. The electronic heat capacity contribution reveals an increase of the density of states at the Fermi level as the Co content is increased. For x = 0 a low dimensionality magnetic transition attributed to the Nd sublattice is observed. The substitution of Ni by Co (1  x < 3) induces interaction disorder on the Nd sublattice. For Nd3Ni13B2 an estimation is given for the molecular field of Hm = 54 kG and the exchange constant of J/kB = 4.1 K.

Abstract: Mechanical properties of a Ti2AlNb-based intermetallic alloy both at room and elevated temperatures were considerably improved due to formation of a homogeneous microstructure with the average grain size of about 300 nm. At room temperature, elongations up to 25% were obtained and the ultimate strength reached 1400 MPa. The alloy exhibited superplastic behavior in the temperature range of 850-1000°C. The maximum elongation of 930% and steady state flow stress 50 of about 125 MPa were obtained at 900°C and strain rate of 4.210-3 s-1. The nanostructured material was used for production of intermetallic sheets and multilayer composite plates consisting of alternating layers of orthorhombic intermetallic and commercial high temperature titanium alloy. Ti2AlNb-based sheets and composites exhibited improved mechanical properties.