Abstract
Interfaces play a crucial role in influencing the mechanical properties of Mg alloys.For Mg-Li dual-phase alloy,the type of interfaces is complex,which includes both grain boundary and phase boundary,and the influence of such interfaces on the damage nucleation is yet to be explored.In this paper,in-situ scanning electron microscopy(SEM)based measurements were carried out to investigate the meso-scale damage nucleation mechanisms of the Mg-6Li dual-phase alloy.Results show that 94.8％of cracks are nucleated at the α-Mg grain boundary in the post-uniform elongation stage,while 5.2％are at phase boundary and almost no crack at the β-Li grain boundary.The initiation of α-Mg grain boundary cracks is attributed to strain incompatibility,which induces micro-strain localization,and then causes grain boundary sliding(GBS)and crack nucleation.Deformation compatibility analysis reveals that the geometric compatibility factor(Mk)can be used to predict the nucleation of α-Mg grain boundary crack.When Mk is lower than 0.075,α-Mg grain boundary cracks tend to form.Few cracks are generated at the phase boundary is due to the mild strain partitioning between α-Mg phase and β-Li phase and may also be partly attributed to multiple slip systems in body-centered cubic(BCC)-structured β-Li phase,which can accommodate well with the deformation of adjacent α-Mg phase.
基金项目
National Natural Science Foundation of China(52005412)
National Natural Science Foundation of China(52305506)
National Natural Science Foundation of China(U2241231)
Fundamental Research Funds for the Central Universities(D5000230081)
NETL
NSTL
万方数据