DIFFERENTIAL THERMAL ANALYSIS AND THE MECHANISMS OF MINOR ADDITIONS IN SUPERALLOYS.

Abstract

DTA can be used to complement the traditional techniques of extraction and x-ray diffraction in defining solid-state carbide reactions. Varying the hafnium concentration from 0 to 2% in MAR M-200 resulted in marked differences in DTA response, both in the solid-state and during melting. The hafnium level was also observed to influence structure and stress-rupture properties. The thermograms of a cast alloy doped with four levels of boron suggest that property improvements attributed to boron may be able to be related to the alteration of phase reactions.