화학공학소재연구정보센터
Materials Science Forum, Vol.475-479, 2623-2626, 2005
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 beta-NiAl phase, interdendritic gamma/gamma', gamma' phase transient layer and alpha-Cr precipitation in beta-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.