Microstructure and Mechanical Properties Change with Cold Rolling of New Ti-13Nb-1.5Ta-3Mo Alloy

Abstract

In this paper, a new metastable Titanium alloy in the Ti-Nb-Ta-Mo system has been successfully produced using both the d-electron and Moeq concept. The influence of cold rolling on the microstructure and hardness was investigated. The alloy was fabricated by arc melting, cold rolled up to 90% reduction in thickness and characterized using X-ray diffraction (XRD), optical microscope and Vickers microhardness. The XRD peaks depicted both β and α′′ phases in all the cold rolled specimens. The hardness of the alloy increased with increasing cold rolling reduction thickness. An excellent plasticity (≥ 65%) and compressive strength up to (2.9 GPa) was achieved with low Young’s modulus (31 GPa) and no failure or crack on the alloy. Also, the alloy demonstrated a high compressive true strength coefficient (k ≈1426 MPa) along with improved strain hardening index (n ≈ 0.41). Based on the XRD, optical microscope and microhardness indentation micrographs, the deformation mechanism of Ti-13Nb-1.5Ta-3Mo was found to be a combination of stress induced transformation, mechanical twinning and slipping.