J. Mater. Sci. Technol. ›› 2025, Vol. 211: 171-178.DOI: 10.1016/j.jmst.2024.05.050

• Research Article • Previous Articles     Next Articles

Abnormally enhanced displacement burst at elevated temperatures of AZ31 magnesium alloy during nanoindentation

Song-Yu Yana, Zhang-Jie Wangb,*, Zhi-Wei Shana,*   

  1. aCenter for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, PR China;
    bCenter for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, PR China
  • Received:2024-02-23 Revised:2024-05-10 Accepted:2024-05-11 Published:2025-03-10 Online:2024-06-14
  • Contact: * E-mail addresses: zhangjiewang@mail.xjtu.edu.cn (Z.-J. Wang), zwshan@mail.xjtu.edu.cn (Z.-W. Shan).

Abstract: The unveiling of temperature effects on the deformation behaviors of wrought magnesium (Mg) alloys is beneficial for optimizing the hot forming parameters of these alloys with limited room temperature (RT) formability. In the present work, we performed nanoindentations on individual grains of textured wrought AZ31 alloy along the normal direction (ND) from RT to 300 °C to investigate the intrinsic non-basal dislocation behaviors at various temperatures. Interestingly, we observed abnormally enhanced nanoindentation displacement bursts (pop-ins) at elevated temperatures ranging from 150 to 250 °C, which is beyond the general scenario that higher temperatures typically result in smoother plastic flow. The bursts exhibited Gaussian-like statistics, which differ from the well-reported bursts with power-law size distributions resulting from the destruction of jammed dislocation configurations. Through transmission electron microscopy (TEM) examination of the microstructure beneath the indentation just after the burst, we found that the abnormal displacement bursts originated from the heterogeneous nucleation of prismatic screw 〈a〉 dislocations due to the exhaustion of dislocation sources within the specified temperature range.

Key words: Nanoindentation, Pop-in, Gaussian-like distribution, Dislocation nucleation, Prismatic slip