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.