The effect of boron addition on brittle-to-ductile transition temperature and its strain rate sensitivity in gamma titanium aluminide

Author: Wang Y.   Lin T. L. Lin D.   Law C.C.  

Publisher: Springer Publishing Company

ISSN: 0022-2461

Source: Journal of Materials Science, Vol.35, Iss.12, 2000-06, pp. : 3083-3087

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Abstract

Temperature dependence of tensile properties of Ti–47Al–2Mn–2Nb–0.8TiB_2 alloy was investigated and brittle-to-ductile transition temperature (T_BD) was evaluated accordingly within the strain rate range from 10^−5 to 10^−1 s^−1. T_BD and its strain rate sensitivity in Ti-47Al-2Mn-2Nb-0.8TiB_2 alloy were compared with those in Ti-47Al-2Mn-2Nb alloy. It is found that the minor addition of 1.0 at% boron reduces T_BD by more than 100 K and that T_BD in both alloys shows a positive sensitivity to the strain rate. But the B-doped alloy has a lower BDT activation energy (256 kJ/mol) than that of B-free alloy (324 kJ/mol). The effect of boron on T_BD and its strain rate sensitivity is attributed to the reduction in the grain size.