The role of mechanical loading in bcc-hcp phase transition: tension-compression asymmetry and twin formation

In response to temperature or pressure changes, many body-centered cubic (bcc) materials undergo martensitic bcc-hcp phase transformation, which is known to produce rich martensite microstructure with internal twins. Mechanical loading is also known to have a huge impact on martensitic phase trans-formation. In this work, we integrate atomistic simulations with theoretical calculations to investigate the effect of mechanical loading on the martensite microstructure. The calculations of deformation gradients and transformation strains reveal that the { 10 1 over line 1 } transformation twins and { 10 1 over line 2 } transformation twins are favored by opposite loading directions. Furthermore, the initial { 112 } twin in the bcc phase is trans-formed into { 11 2 over line 2 } and { 11 2 over line 1 } twins after the phase transformation. The results reveal the critical role of mechanical loading in the formation of the specific transformation twinning, which could offer a novel strategy to engineer twin microstructure using designed thermomechanical processing.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the effect of mechanical loading on martensite microstructure and reveals the critical role of mechanical loading in the formation of specific transformation twinning, which could offer a novel strategy for engineering twin microstructure using designed thermomechanical processing.