Softening Behaviors of Severely Deformed Zn Alloy Studied by the Nanoindentation

Jiangjiang Hu,Xu Sun,Taihua Zhang,Shuo Sun,Yusheng Zhang,Shuang Han,Guangjian Peng,Wei Zhang

doi:10.3390/coatings10090803

Abstract

Zamak 3 alloy treatment by sliding-friction treatment (SFT) was investigated by nanoindentation to explore the influence of microstructure and strain rate on nanoscale deformation at room temperature. The results show that obvious material softening occurs in the ultrafine-grained (UFG) Zn alloy and strain-hardening happens in the twinning-deformed layer, respectively. It can be concluded that almost constant values of V in the UFG Zn alloy contribute to the dislocations moving along the grain boundary (GB) not cross the grain interior. In the twinning-deformed layer, the highly frequent dislocation–twinning boundary (TB) interactions are responsible for subsequent inverse Cottrell–Stokes at lower stress, which is quite different from dislocation–dislocation reaction inside the grain in their coarse-grained (CG) counterpart.

Highlights

Grain size (d) refinement is a well-known strengthening mechanism for improving the mechanical properties of metallic materials [1,2,3,4,5,6,7]
Conrad and coworkers have have concluded that grain boundary (GB) shear mechanism have been proposed for the observed concluded grainHall–Petch boundary (GB)
Our results have shown that all the V exhibit a slightly decrement that can be treated as a constant value, which implies that dislocations probably move along the GB not crossing the grain interior

Summary

Introduction

Grain size (d) refinement is a well-known strengthening mechanism for improving the mechanical properties of metallic materials [1,2,3,4,5,6,7]. Some researchers have reported that grain refinement produced by severe plastic deformation (SPD). Would give rise to the material softening in some metals after serious work hardening [8,9]. This means that traditional grain refinement strengthening mechanism such as grain boundaries (GBs) act as strong barriers to dislocation slipping would be in failure in these materials. Some other deformation modes would dominate the plastic strain, which need to be further understood. Mazilkin et al have found the pronounced softening in the binary

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