Papers by Keyword: Ni-Al

Abstract: The utilization of nickel aluminide compounds in high-temperature structural applications is advantageous due to their desirable properties. One efficient method for producing nickel aluminide samples with desirable chemical reactions using minimal energy is reactive sintering. In this study, Ni-Al (20 wt.%-80 wt.%) compounds were fabricated by initially cold pressing them, followed by reactive sintering. The reactive sintering process resulted in the formation of NiAl₃ and Ni₂Al₃ phases within the Ni-Al compounds. The microstructure, porosity, and hardness of the samples were thoroughly examined and analyzed. Generally, the compounds produced through reactive sintering exhibited significant porosity attributed to shrinkage and the Kirkendall effect. Microstructural analysis confirmed the presence of porosity, NiAl₃, and Ni₂Al₃ phases. The sintered sample processed at 400 °C demonstrated higher density and hardness. Additionally, the wear test indicated a low wear rate and friction coefficient for the sintered sample processed at 400 °C.

Abstract: Most semiconductor devices require low-resistance ohmic contact to p-type doped regions. In this work, we present a semi-salicide process that forms low-resistance contacts (~10^-4 Ω cm²) to epitaxially grown p-type (>5×10¹⁸ cm^-3) 4H-SiC at temperatures as low as 600 °C using rapid thermal processing (RTP). The first step is to self-align the nickel silicide (Ni₂Si) at 600 °C. The second step is to deposit aluminium on top of the silicide, pattern it and then perform a second annealing step in the range 500 °C to 700 °C.

Abstract: We explored a new type alloy EAM potential (CLI-EAM) that the value of atomic electron density and pair potential between distinct atoms are obtained by Chen’s lattice inversion based on first-principles calculations. The alloy CLI-EAM potential acquired from NiAl alloy can also apply in Ni3Al successfully and the results of basic properties agreed with the experiments. The results of formation energy of point defects of NiAl and Ni₃Al alloy indicate that the structural defects are anti-site defects of Al when enrichments of Al atoms.

Abstract: A calculation of the interface energy for the Ni-Al binary alloy, including the inter-phase boundary (IPB) energy and the anti-phase boundary (APB) energy, has been performed using the Cluster Variation Method (CVM) with the tetrahedron approximation within the temperature range of 600°C~1300°C. The calculated IPB energies range between 8 and 13 mJ/m2, while the APB energies range between 24 and 46 mJ/m2. Additionally, the dependence of the average composition and the order parameter on distance with the compositionally diffuse interfacial regions has been computed. The calculation also shows the width of the diffuse IPB increases with the temperature linearly.

Abstract: Formation of a protective scale such as chromia or alumina is a prerequisite for an excellent oxidation performance of high-temperature materials. Based on this principle, a novel concept of designing chromia- or alumina-forming nanocomposites by means of nanocomposite electrodeposition of Ni with Cr or/and Al nanoparticles were proposed. A brief review on the high temperature oxidation performance of such novel electrodeposited nanocomposites like Ni-Cr, Ni-Al and Ni-Cr-Al is presented.