Influence of Al addition on electrical resistivity and phase constitution in quenched Ti-20 mass%V alloy

Abstract

Electrical resistivity anomalies in β type Ti alloys including negative temperature dependence were previously interpreted by fully reversible formation and disappearance of athermal ω phase with cooling and heating. In the present work, influence of Al addition up to 10 mass% on some properties of Ti~20%V alloy in as quenched state from β region were investigated. Resistivity increases with concentration of solute Al. Addition of 3%A1 changes the temperature-resistivity curve of Ti-20%V alloy, which had a resistivity maximum between 77 K and room temperature, to the curve having negative temperature coefficient in whole of the above temperature range. In alloys below 5%A1, hardness decreases slightly with Al addition, namely no solid solution hardening by Al can be observed. However, the hardening appears above 8%A1 clearly. These results suggest that the starting, perhaps also finishing, temperature of athermal ω phase formation is lowered and that the amount of athermal ω phase at room temperature is decreased by the Al addition. This interpretation is qualitatively confirmed by electron diffraction. © 1992, The Japan Institute of Light Metals. All rights reserved.