Precipitation in Incoloy alloy 909

Abstract

The precipitation of second phases in Incoloy 909 has been studied using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The compositions and crystal structures of several second phases were determined by analytlcal electron microscopy. A time–temperature–transformation diagram was constructed. The Si addition was found to promote the precipitation of an Fe2Nb type Laves phase during casting and thermal processing, and the formation of Si rich orthorhombic phase at high aging temperatures. Both types of precipitate are considered to enhance the rupture properties of the alloy.MST/1748