Abnormal grain growth in textured FeAl intermetallics

Abstract

Abnormal grain growth has been observed in powder processed, hot extruded, B2 FeAl alloys which display significant wire textures. This study uses X-ray inverse pole figures and electron backscatter diffraction patterns to examine the relationship between the texture and this abnormal grain growth. Texture analysis has been performed on samples heat treated at various temperatures both above and below the critical temperature for abnormal grain growth initiation. The powder processed samples initially have a strong (111) wire texture which is generally retained after heat treatments of up to 1000 °C. At heat treatments of 1050 °C and higher this texture disappears and instances of abnormal grain growth are observed. In contrast to the powder processed alloys, abnormal grain growth has not been observed in cast and extruded FeAl alloys. Backscattered Kikuchi patterns have been used to determine the micro-texture of the alloys so that the relationship between the initial wire texture and the abnormal grain growth may be examined. The results of the texture and micro-texture analysis are discussed in light of current theoretical models for grain growth.