The Al-rich region in the Y-Ni-Al system: microstructures and phase equilibria

The Al-rich region of the Y-Ni-Al ternary system has been investigated main ly by using different micrographic techniques. In the range 60 < at% Al < 1 00 the 500 degrees C isothermal section has been partially defined. The com pound Y4Ni6Al23 and its role in phase equilibria have been highlighted. The YNi3Al16 phase previously suggested has not been confirmed. Two ternary ti e-triangles in this region have also been defined: Al + NiAl3 + Y4Ni6Al23 a nd Al + YAl3 + Y4Ni6Al23. Two ternary eutectic equilibria: El, Ni-rich: at about 96.5 at% Al, 2.6 at% Ni, 0.9 at% Y and E-2, Y-rich: at about 96.0 at% Al, 1.0 at% Ni, 3.0 at% Y have been identified. The crystallization behavi our of the Al-rich alloys is described and typical micrographic appearances presented. (C) 2000 Elsevier Science Ltd. All rights reserved.