Y. Wang et al., Brittle-to-ductile transition temperature and its strain rate sensitivity in a two-phase titanium aluminide with near lamellar microstructure, J MATER SCI, 34(13), 1999, pp. 3155-3159
The temperature dependence of tensile properties of a two-phase titanium al
uminide with nearly lamellar microstructure has been investigated and britt
le-to-ductile transition (BDT) temperatures (T-BDS) have been determined un
der different strain rates from 10(-5) to 10(-1) s(-1). It is found that T-
BD rises with the increase of strain rate. From the positive strain rate se
nsitivity of T-BD, the apparent activation energy of BDT is determined to b
e 324 kJ/mol by means of Zener-Hollomon factor. The determined activation e
nergy approximates to the activation energies of self-diffusion of Ti atoms
, and inter-diffusion of Ti and Al atoms in TiAl phase. The approximation,
fractography analysis and theoretical calculation using the Nabarro Model a
dd up to the speculation that the BDT of the alloy is controlled by disloca
tion climbing. (C) 1999 Kluwer Academic Publishers.