A Ni-25Al-25Cr (at.%) alloy was directionally solidified under Ar atmosphere in an A1(2)O(3)-SiO2 ceramic mold by the standard Bridgman method. The microstructure of the as-fabricated alloy was studied using optical microscopy, X-ray diffraction and scanning electron microscopy. The alloy was composed of beta-NiAl dendritic arms, alpha-Cr interdendritic regions, fine alpha-Cr particles in the dendritic arms, and beta-NiAl + alpha-Cr eutectic in the interdendritic regions. The mechanical properties were studied by tensile tests in the temperature range 1123 - 1373 K. The results showed that the alloy exhibits superplastic behavior at appropriate testing conditions. The balance between work hardening (by dislocation glide) and work softening (by dynamic recovery and recrystallization) is responsible for the large tensile elongation of the alloy.
部门归属
chinese acad sci, inst met res, shenyang 110016, peoples r china.;guo, jt (reprint author), chinese acad sci, inst met res, 72 wenhua rd, shenyang 110016, peoples r china;jtguo@imr.ac.cn
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