Microstructure and Mechanical Property of the Directionally Solidified NiAl-Cr(Mo)-Hf/Ho Alloy

摘要

The microstructure and mechanical property of directionally solidified NiAl-Cr(Mo)-Hf/Ho alloy were studied. The results indicate that the alloy is composed of NiAl matrix and Cr(Mo) phase, the dispersion of Hf is identical with the NiAl matrix, and at the cell boundary, the dispersion of Ho is disperse. As the pull speed increase from 8 mm/min to 15 mm/min, the size of eutectic cell decreases, the lamellar size descends, too. After the homogenization heat treatment at 1473 K for 20 h, the size of eutectic cell increases, and the second phase precipitates, the hardness of the alloy decreases.