Phase Equilibria in the Ni-Al-Sn Ternary System at 800 and 1000 °C

The phase equilibria in the Ni-Al-Sn ternary system at 800 and 1000 degrees C was investigated by electron probe microanalysis and X-ray diffraction. The results show that: (1) No ternary compound is found at 800 and 1000 degrees C. (2) The Ni-Al side presents four binary compounds including NiAl, Ni3Al, Al3Ni and Al3Ni2 phases. The solubilities of Sn in the binary NiAl and Ni3Al phases are 3.1 at% and 14.7 at% at 800 degrees C, and 3.0 at% and 8.0 at% at 1000 degrees C, respectively. As for the binary Al3Ni and Al(3)Ni2 phases, the solubilities of Sn are almost negligible. (3) The Ni-Sn side displays three binary compounds including Ni3Sn(r), Ni3Sn(h) and Ni3Sn2(h). The Ni3Sn(r) phase is stable at 800 degrees C dissolving 4.2 at% Al, but it is replaced by the Ni3Sn(h) phase with a 5.5 at% Al solubility at 1000 degrees C. The solid solubility of Al in Ni3Sn2(h) is 8.4 at% and 12.1 at% at 800 and 1000 degrees C, respectively. (4) The Al-Sn side is occupied by an interconnected liquid region having only similar to 1 at% Ni solubility.