Reorientation Induced Plasticity (RIP) in high-strength titanium alloys: An insight into the underlying mechanisms and resulting mechanical properties

The present paper aims at providing a fine-scale analysis of the Ti-4.5Al-2.5Fe-0.25Si alpha+alpha'+beta retained micro-structures to give insight into the link between the microstructural characteristics of the alloy (phase fraction and chemistry, grain size, etc.) and the deformation mechanisms at play. These microstructures were found to exhibit outstanding work-hardening capabilities that have the great potential to be obtained simultaneously with a high yield strength when the microstructural features are carefully optimized. Ex-situ analyses coupled with TEM revealed the simultaneous occurrence of Reorientation Induced Plasticity (RIP) into the self-accommodated Fe-enriched alpha' martensite, TRansformation Induced Plasticity (TRIP) of the beta retained phase and TWinning Induced Plasticity (TWIP) of the alpha phase that add to dislocation glide. The Fe-enriched martensite has the remarkable capability to induce reorientation through two distinctive mechanisms: by the motion upon deformation of the intervariant boundary associated to the [4 5 1 3]alpha ' Type II twin, a rather classical mechanism although not often reported into alpha'; but more surprisingly into such a fine phase, by the creation and growth upon deformation of {1012}1011 alpha ' twins. A 3-scale mechanical contrast is proposed to explain the remarkable work-hardening rates achieved. Reorientation is shown to be a key microstructural feature for the development of Ti alloys with su-perior mechanical properties.

Automated summary

The present study provides a detailed analysis of the microstructural characteristics of the Ti-4.5Al-2.5Fe-0.25Si alloy and its deformation mechanisms. The alloy exhibits remarkable work-hardening capabilities when the microstructural features are optimized. The Fe-enriched martensite induces reorientation through the motion of intervariant boundaries and the creation and growth of alpha' twins, contributing to the material's superior mechanical properties.