{10-12} twinning transfer behavior in compressed high-purity hafnium

Abstract

The interaction between twins and grain boundaries (GBs) significantly influences material deformation and fracture behavior. In the present study, high-purity hafnium (Hf) was subjected to compression at both room temperature and under liquid nitrogen cooling conditions. Twinning transfer (TT) behavior of {10–12} < −1011 > extension twin was thoroughly and statistically investigated. Results show that compression temperature affects the misorientation angle (MA) for TT. Under room temperature compression, twins can transfer across GBs with MAs below 30° and partially transfer across GBs with MAs between 30° and 50°. When compressed under liquid nitrogen cooling, twins can traverse the GBs with MAs below 40° and partially traverse the GBs with MAs above 40° and with a maximum MA of 77°. The MA, Schmidt factor (SF) value, and geometrical compatibility parameter m’ of twinning systems in neighboring grains influence the TT. Favorable conditions for TT include low MAs, high SF and m’ values. Stress concentration caused by incoming twins can be alleviated through TT with high m’ at GBs with low MAs. For GBs with high MAs, stress concentration can also be alleviated through TT or twinning-slipping transfer with high m’. Extension and growth of outgoing twins contribute to further stress concentration relief.