Growth of Multicomponent Composites from the Melt.
Annual summary technical rept. 1 Mar 71-29 Feb 72,
MASSACHUSETTS INST OF TECH CAMBRIDGE
Pagination or Media Count:
A simple constitutional supercooling analysis is given for predicting interface stability in plane front solidification of ternary alloys containing one, two, or three phases. It is concluded that polyphase composites can be grown from ternary alloys by plane front solidification provided thermal gradient is sufficiently high, growth rate is low, convection is low and kinetic undercooling is small. Calculated examples of conditions required for stability are given for three-phase alloys from the aluminum-rich corner of the Al-Cu-Ni system. It is seen that the most stable compositions with respect to interface breakdown lie nearly, but not exactly, on lines of two-fold saturation. Ternary alloys from the Al rich corner of the Al-Cu-Ni system were unidirectionally solidified under a wide variety of growth conditions. Plane front solidification was achieved at sufficiently high thermal gradients and slow growth rates. Conditions necessary to cause planar interface breakdown in both two and three phase alloys compare well to those predicted by a simple constitutional supercooling criterion. Author
- Properties of Metals and Alloys