Micropillar compression deformation of single crystals of Fe3Ge with the L1(2) structure

The plastic deformation behavior of single crystals of Fe3Ge with the L1(2) structure has been investigated at room temperature as a function of crystal orientation by micropillar compression tests. In addition to slip on (010), slip on (111) is observed to occur in Fe 3Ge for the first time. The CRSS (critical resolved shear stress) for (111)[10 (1) over bar] slip, estimated by extrapolating the size-dependent strength variation to the 'bulk' size, is similar to 240 MPa, which is almost 6 times that (similar to 40 MPa) for (010)[10 (1) over bar] slip similarly estimated. The dissociation scheme for the superlattice dislocation with b= [10 (1) over bar] is confirmed to be of the APB (anti-phase boundary)-type both on (010) and on (111), in contrast to the previous prediction for the SISF (superlattice intrinsic stacking fault) scheme on (111) because of the expected APB instability. While superlattice dislocations do not have any preferential directions to align when gliding on (010) (indicative of low frictional stress at room temperature), the alignment of superlattice dislocations along their screw orientation is observed when gliding on (111). This is proved to be due to thermally-activated cross-slip to form Kear-Wilsdorf locks, indicative of the occurrence of yield stress anomaly that is observed in many other L1(2) compounds such as Ni3Al. Some important deformation characteristics expected to occur in Fe3Ge (such as the absence of SISF-couple dissociation and the occurrence of yield stress anomaly) will be discussed in the light of the experimental results obtained (APB energies on (111) and (010) and CRSS values for slip on (111) and (010)). (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd.

Automated summary

The plastic deformation behavior of single crystals of Fe3Ge with the L1(2) structure was investigated at room temperature using micropillar compression tests. It was found that slip on (111) has occurred in Fe3Ge for the first time, and the dissociation scheme for superlattice dislocations was confirmed to be of the APB-type on both (010) and (111) faces.