The creep behaviour of some silicon-containing titanium alloys

Abstract

An investigation has been made of the secondary creep behaviour of binary TiSi alloys containing ~ 0.6 and 1 wt.% Si and of a Ti-5 wt.% Zr1 wt.% Si alloy. The Ti-1 wt.% Si alloy, as-quenched from the β-phase region, showed a high resistance to creep; this is associated with silicon in solid solution and the consequent dynamic strain ageing effect arising from a silicon-interstitial atom interaction. The precipitation of Ti 5Si 3 by ageing reduced the creep resistance. The presence of zirconium substantially improved the creep resistance in the aged condition. Values of the “stress exponent” at strain rates >10 −10 s −1 were in the range 5–20, but showed no systematic variation with alloy composition or heat treatment. Values of the apparent activation energy for secondary creep depended on the silicon content, and were greater than those for diffusion of substitutional elements in titanium.