Impact strength of γ-TiAl intermetallic compound

The compressive strength of an intermetallic compound γ-TiAl, was characterized at temperatures from 77 K to 1 073 K and at strain rates from 10-4s-1 to 103s-1. At low temperatures, flow stress increased with decrease of temperature and with increase of strain rate, and an abnormal increase of stress was observed, probably due to the dynamic interaction of dislocations with lattice defects at relatively high temperatures where negative strain rate dependence of stress was also observed. The higher the strain rate, the more the interaction becomes marked at higher temperatures; consequently, a minimum strength at intermediate temperatures can be expected. The concept of a thermally activated process gives a plausible explanation of the experimental results in the given temperature ranges, and allows prediction of the dynamic behaviors of this kind of material.