Comments on “steady-state creep deformation of investment cast near-gamma titanium aluminide”

摘要: In a recent article, the creep behavior of near-gamma Ti-48Al-2Nb-2Cr (at.%) cast alloy was investigated. The results and analyses are criticized as follows: Firstly, it is difficult to measure strain rates slower than 10[sup [minus]8]s[sup [minus]1] by conducting tests for only' 100 hours, since this corresponds strains below 0.0036. Secondly, activation energies at 103 172 MPa calculated authors incorrect. At MPa, energy [approximately]240 kJmol[sup rather 300 (data from Fig. 2). stress exponents clearly different each other three temperatures; hence, an associated with single deformation mechanism cannot be determined. Thirdly, claim that in region where exponent, n, equal three, dislocation pipe diffusion controlling stress-assisted diffusional mechanism...'. This most likely incorrect since, when (Nabarro-Herring/Coble) dominating behavior, no motion expected; consequence, density should remain constant applied low regime. conclusion, determine mechanism(s) thismore » based on data presented.« less