The Effect of Ti/Ta Ratio and Processing Routes on the Hardness and Elastic Modulus of Porous TiNbZrTa Alloys

TiNbZrTa alloys are promising for multidisciplinary applications, such as refractory and biomedical purposes, due to their high thermal stability and non-toxicity. Hardness and elastic modulus are among the key features for their adequate industrial applications. The influence of porosity and Ti/Ta ratio were investigated on TiNbZrTa alloys produced by three different processing routes, i.e., (i) blend element and posterior press and sintering (BE + P&S); (ii) mechanical alloying with press and sintering (MA + P&S); and (iii) arc melting and casting. Porosity decreased in the following order: casting < MA + P&S < BE + P&S. The total porosity of alloys increased with increasing Ta contents, i.e., by lowering the Ti/Ta ratio. However, the Ti/Ta ratio did not considerably affect the bonding energy or the elastic modulus. Hardness was increased significantly in dense alloys compared to porous ones. However, porosity and Ti/Ta ratio did not show a clear trend in hardness among the porous alloys

Mechanical and Electrochemical Properties Comparison of Additively Manufactured Ti-6Al-4V Alloys by Electron Beam Melting and Selective Laser Melting

This work involves additively manufactured Ti-6Al-4V alloys, which are widely used in automobile, biomedical, and aircraft components for a comparison of the microstructure–properties relationship between electron beam melted (EBM) and selective laser melted (SLM) alloys after hot isostatic pressing treatment. We carried out microstructural, mechanical, and electrochemical measurements on both alloys. They showed comparable α and β phase contents with slightly higher lattice parameters in the EBM sample compared to the SLM. The EBM sample showed higher yield strength and uniform elongation due to the activation of multistage defects-driven strengthening and strain hardening mechanisms. Cracking during the tensile test nucleated mainly at the α phase near high-mechanical mismatch α/β interfaces. This mechanism was consistent with the reported generation of hetero-deformation-induced strengthening and strain hardening. Both alloys showed similar electrochemical behavior, but the SLM sample was more susceptible to corrosion than the EBM alloy