The Microstructure and Mechanical Properties of Directionally Solidified NiAl-15Cr Alloy at Various Temperatures
The microstructure and tensile mechanical properties of directionally Solidified NiAl-15Cr alloy at various temperatures have been investigated in this paper. The results reveal that the microstructure consists of dendritic β-NiAl phase, interdendritic γ/γ’, γ’ phase transient layer and α-Cr precipitation in β-NiAl phase. With the increase of temperature obvious Brittle-Ductile-Transition (BDT) behavior is observed and the BDT temperature (BDTT) is sensitive to initial strain rate. When the initial strain rate increases by two-order magnitude, the BDTT has an approximate 150K increase. In the temperature range of 1123-1373K, the alloy exhibits good tensile plasticity and poor strength comparing with the NiAl/Cr(Mo,Hf) alloy. Superplastic-like deformation behavior with large elongation (exceed 200%) is achieved at 1323K. The balance between strain hardening (by dislocation glide) and strain softening (dynamic recover and recrystallization) is responsible for the large tensile elongation of this alloy.
Z.Y. Zhong, H. Saka, T.H. Kim, E.A. Holm, Y.F. Han and X.S. Xie
G. Y. Zhang et al., "The Microstructure and Mechanical Properties of Directionally Solidified NiAl-15Cr Alloy at Various Temperatures", Materials Science Forum, Vols. 475-479, pp. 2623-2626, 2005