In this paper, the electronic, mechanical and thermodynamic properties of AlNi₂Ti are studied by first-principles calculations in order to reveal the influence of AlNi₂Ti as an interfacial phase on ZTA (zirconia toughened alumina)/Fe. The results show that AlNi₂Ti has relatively high mechanical properties, which will benefit the impact or wear resistance of the ZTA/Fe composite. The values of bulk, shear and Young’s modulus are 164.2, 63.2 and 168.1 GPa respectively, and the hardness of AlNi₂Ti (4.4 GPa) is comparable to common ferrous materials. The intrinsic ductile nature and strong metallic bonding character of AlNi₂Ti are confirmed by B/G and Poisson’s ratio. AlNi₂Ti shows isotropy bulk modulus and anisotropic elasticity in different crystallographic directions. At room temperature, the linear thermal expansion coefficient (LTEC) of AlNi₂Ti estimated by quasi-harmonic approximation (QHA) based on Debye model is 10.6 × 10⁻⁶ K⁻¹, close to LTECs of zirconia toughened alumina and iron. Therefore, the thermal matching of ZTA/Fe composite with AlNi₂Ti interfacial phase can be improved. Other thermodynamic properties including Debye temperature, sound velocity, thermal conductivity and heat capacity, as well as electronic properties, are also calculated.

This work investigated the microstructure and mechanical property of high-boron multi-component alloy with Fe, B, C, Cr, Mo, Al, Si, V, Mn and different contents of Ti. The results indicate that the as-cast metallurgical microstructure of high-boron multi-component alloys consist of ferrite, pearlite and borocarbide. In an un-modified alloy, continuous reticular structure of borocarbide is observed. After titanium addition, the structure of borocarbide changes into a fine and isolated morphology. TiC is the existence form of titanium in the alloy, which acts as the heterogeneous nuclei for eutectic borocarbide. Moreover, impact toughness of the alloy is remarkably improved by titanium modification.

In this study, the as-cast and heat treated microstructures, hardness and impact toughness of high boron high speed steel with Fe-2.0wt.% B-0.4wt.% C-6.0wt.% Cr-4.0wt.% Mo-2.0% Al-1.0wt.% Si-1.0wt.% V-0.5wt.% Mn-xwt.% Ca (x=0.00, 0.08, 0.16, 0.24) is systematically investigated. The experimental results reveal that the as-cast microstructure of high boron high speed steel consists of α-Fe as matrix and eutectic borocarbide M2(B,C) (M=Fe, Cr, Mo, V, Mn). Borocarbide presents a continuous and reticular structure in alloy without calcium modification. After calcium modified, hardness of matrix increases because of solid solution strengthening. Besides, the continuous network of borocarbide is destroyed and possesses an isolated, fine and spherical structure. Calcium in high boron high speed steel has strong surface activity, which exists in the form of solid solution and mainly segregates at the interface between matrix and borocarbide. As a significant discovery, to calcium modified high boron high speed steel, the heat treatment can ulteriorly improve the shape and size of borocarbide. Moreover, the impact toughness of high boron high speed steel is remarkably improved by calcium modification. All of the modified alloys as well as the unmodified one perform the mechanism of complex of brittle and ductile fracture.

In this work, the microstructure, alloying element distribution, and borocarbide mechanical properties of high-boron multi-component alloy with Fe-2.0 wt.%B-0.4 wt.%C-6.0 wt.%Cr-x wt.%Mo-1.0%Al-1.0 wt.%Si-1.0 wt.%V-0.5 wt.%Mn (x = 0.0, 2.0, 4.0, 6.0, 8.0) are investigated. The theoretical calculation results and experiments indicate that the microstructure of high-boron multi-component alloy consists of ferrite, pearlite as a matrix and borocarbide as a hard phase. As a creative consideration, through the use of first-principles calculations, the comprehensive properties of borocarbide with different molybdenum concentrations have been predicted. The calculations of energy, state density, electron density and elastic constant of Fe₂B crystal cell reveal that substitution of the molybdenum atom in the Fe₂B crystal cell can remarkably improve its thermodynamic stability, bond strength, and covalent trend. For verifying the accuracy of this theoretical calculation, nano-indentation testing is carried out, the results of which indicate that the actual properties of borocarbide present favorable consistency with the theoretical calculations.