Improving embrittlement in the Ti-Al-C MAX phase system: A composite approach for surface severe plastic deformation

Ti2AlC and Ti3AlC2 belong to an interesting family of layered compounds called MAX phases. A composite approach is tested here to improve the intrinsic brittle behaviour of such compounds. To this end, a bulk MAX compound and a MAX/TiAl2 composite have been deformed under surface severe plastic deformation (SSPD) by surface mechanical attrition treatment (SMAT). Grain delamination and grain decohesion occurred to a depth of 100 mu m below the surface for the bulk compound. Resulting cracks and grain pullouts were witnessed by a decrease in the surface and sub-surface hardness. Comparatively, the presence of intergranular TiAl2 effectively prevented such failure for the composite. Thus, the SSPD of this cohesive composite created a surface hardening (+60%) gradient extending down to a depth of 250 mu m. Witness marks of plasticity were revealed in both the MAX and TiAl2 phases. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Ti2AlC and Ti3AlC2 are part of the MAX phases, a family of layered compounds. The study tests a composite approach to improve the brittleness of these compounds. Surface severe plastic deformation (SSPD) was conducted on a bulk MAX compound and a MAX/TiAl2 composite using surface mechanical attrition treatment (SMAT). The presence of intergranular TiAl2 effectively prevented failure in the composite, resulting in a surface hardening gradient extending down to a depth of 250 μm.