In-situ measurements of grain rotation during annealing in ultrafine grained aluminum alloy

V N Danilenko,D V Bachurin,R R Mulyukov

doi:10.22226/2410-3535-2014-4-233-236

Abstract

We present the results of in-situ studies of evolution of grain boundary misorientations in ultrafine grained (UFG) aluminum alloy Al-4%Cu-0.5%Zr during annealing. The structure of the UFG alloy was obtained by severe plastic deformation method. Misorientations between the grains were measured using single reflection technique. It was found that relaxation processes during annealing are accompanied by grain rotation. Analysis of the kinetics of grain rotation in the discrete-dislocation approach has demonstrated a good agreement between the numerical estimates and the experimental data.

Highlights

High internal stresses are typical for ultrafine grained as well as nanocrystalline materials produced by severe plastic deformation method [1,2,3]
During deformation and annealing various relaxation processes occur in these materials such as grain boundary sliding, grain rotation, grain boundary migration etc
Rotation of subgrains in thin films was observed during the heating of the monocrystals of Fe-3 %Si after the cold rolling [10] and during the heating of Al-6 %Ni alloy in the column of the high-voltage electron microscope [11], where the grain rotation was detected by loss of dislocations from low-angle grain boundaries

Summary

Introduction

High internal stresses are typical for ultrafine grained as well as nanocrystalline materials produced by severe plastic deformation method [1,2,3]. During deformation and annealing various relaxation processes occur in these materials such as grain boundary sliding, grain rotation, grain boundary migration etc. Grain rotation as a possible mechanism of microstructure evolution was studied in Ref.[4], where a two-dimensional polycrystalline system was simulated under the influence of finite temperatures, applied strains and external fields. In-situ observation of grain rotations was carried out for nanostructured gold thin films [8] and nanocrystalline copper [9]. Investigation of evolution of the grain boundary misorientations during in-situ annealing of UFG alloy Al-4 Cu-0.5 Zr has shown that relaxation of the microstructure is accompanied by grain rotation [13].

Experimental materials and procedures

Results and discussion

Conclusions