Quantitative investigation on the individual contribution of twinning and dislocation slip to creep in dilute Mg-Y alloys with various grain sizes

Abstract

This work investigated the individual contribution of twinning and dislocation slip to creep in Mg-2 wt%Y alloys with different grain sizes. Three samples with the grain sizes of d = 31.2 μm, d = 63.5 μm and d = 127.7 μm were prepared by regulating the annealing treatment conditions, and the compressive creep tests were conducted at 473 K under 80 MPa along the rolling direction. It was found that the volume fraction of twins and the density of dislocations were continuously increased with increasing creep time regardless of grain size. During the first 50 h, the contribution of twinning was gradually increased while the contribution of dislocation slip was gradually decreased. Afterwards, the contributions of twinning and dislocation slip remained stable with increasing creep time in all samples. In addition, it was suggested that decreasing grain size could reduce the contribution of twinning but enhance the contribution of dislocation slip to creep. The results may provide reliable reference to the understanding and modeling of creep behaviors in Mg-RE alloys.