The Young's modulus (E), Poisson's ratio (ν) and anisotropy parameter (AG) of α' phase, which obtained from different solution treatment and water quenching temperature, were investigated using first-principles calculations based on density functional theory (DFT). The calculation results showed that the Z-axis value of the elastic modulus of α' phase was higher than that of the X-axis and the Y-axis, indicating the elastic modulus of α' phase was anisotropic. It was decreased with increasing the solution treatment and water quenching temperature for the elastic modulus anisotropy of α' phase. In order to verify the calculation results, the elastic modulus anisotropy of macroscopic Ti-6Al-4V alloys, which were treated at 850ºC, 900ºC and 950ºC, were tested by the tensile and the compressive experiments. The experimental results showed the same change tendency with the calculation results. It concluded that the elastic modulus anisotropy of macroscopic alloy could be controlled by the elastic modulus anisotropy of α' phase.
Fe-Cr-Nb-C wear-resistant alloy coatings were successfully fabricated on high-carbon forged steel via coaxial powder feeding laser cladding. The evolution of microstructure and wear resistance with varying Nb content was systematically investigated. The results indicate that appropriate NbC addition markedly modifies the distribution of grain and boundary carbides. As Nb content increases from 2.5 wt% to 3.5 wt%, nanoscale rod-like NbC precipitates form uniformly along boundaries, effectively suppressing the formation of brittle Cr23C6 precipitation. Semi-coherent NbC/matrix interfaces and NbC-induced grain refinement reduce adhesive/abrasive wear, thereby improving hardness and wear resistance. At 4.5 wt% Nb, discrete micron-sized NbC particles form within the grains, yielding optimal performance. However, excessive Nb (≥5.5 wt%) causes NbC agglomeration, inducing stress concentrations and large spallation pits that deteriorate wear resistance. This work highlights NbC morphology as a key factor for tailoring coating properties.
27 September 2023 in Journal of Materials Research and Technology