Microstructural evolution of (TiAl)+Nb+W+B alloy

A newly designed TiAl alloy containing W, Nb, and B was produced through magnetic-flotation-melting method. Mass production of this TiAl-based alloy, 15 kg ingot size, which is quite different from the 0.05 kg small ingot produced by arc-melting, has a large effect on the metallurgical properties, such as the grain size and the phase structures of the alloy. Heat treatments were carefully designed in order to reduce the amount of the high-temperature remaining β phase in the alloy, and to obtain optimal microstructures for mechanical behavior studies. A room-temperature ductility of 1.9 was obtained in the cast TiAl-based alloy after the appropriate heat treatment. The mechanical behavior of the large ingot through mass production of the TiAl-based alloy was largely improved by the alloy design and subsequent heat treatments. © 2011 The Nonferrous Metals Society of China.