Nucleation Mechanism of 40˚&lt;111&gt; Rotated Grains during Recrystallization in Heavily Cold-Rolled Ni&lt;sub&gt;3&lt;/sub&gt;Al Single Crystals

Masahiko Demura,Toshiyuki Hirano,Kyosuke Kishida,Ya Xu

doi:10.4028/www.scientific.net/msf.558-559.183

Abstract

Primary recrystallization textures were examined in the 84% and 95% cold-rolled boron-free Ni3Al single crystals with a Goss texture using the electron backscatter diffraction method. It was found that the main components of the textures in the specimens heat-treated at 873K/0.5h had a 40° rotation relationship about <111> to the original, Goss texture. All the eight variants of 40°<111> rotated grains existed. However, the number density is not even but dependent on whether the rotation axis is identical to the normal of slip planes activated during the prior cold rolling. The ratio of the number density among the variants was same in both the 84% and 95% cold-rolled foils. Based on these results, the formation of these 40°<111> rotated grains was explained assuming the modified multiple twinning mechanism where the annealing twinning occurred at the activated slip planes, followed by the subsequent twinning.

Highlights

We have found an interesting texture evolution with heat treatment in heavily cold-rolled Ni3Al single crystals [1]: disintegration from the cold-rolled texture by primary recrystallization and reintegration into the original, cold-rolled texture by grain growth
It turned out that the texture disintegrated by the primary recrystallization has 40 ̊ rotation relationship about to the original, cold-rolled texture [2], leading to the assumption that 40 ̊ grain boundary (GB) has a high mobility in Ni3Al like fcc metals
There was a spread of the Goss orientation, especially about the normal direction (ND)

Summary

Introduction

We have found an interesting texture evolution with heat treatment in heavily cold-rolled Ni3Al single crystals [1]: disintegration from the cold-rolled texture by primary recrystallization and reintegration into the original, cold-rolled texture by grain growth This phenomenon can be referred to as texture memory effect. It turned out that the texture disintegrated by the primary recrystallization has 40 ̊ rotation relationship about to the original, cold-rolled texture [2], leading to the assumption that 40 ̊ grain boundary (GB) has a high mobility in Ni3Al like fcc metals Based on this assumption, the texture memory effect can be explained as follows. It is, not clear how the 40 ̊ rotated grains were formed during the primary recrystallization

Results

Discussion

Conclusion