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

• Published in: Journal of alloys and compounds 2023-07, Vol.950, p.169946, Article 169946
• Main Authors: Heinzelmeier, Adrien, Guitton, Antoine, Novelli, Marc, Yu, Wenbo, Grosdidier, Thierry
• Format: Article
• Language: English
• Subjects: MAX phases; Mechanics; Mechanics of materials; Physics; Severe plastic deformation (SPD); Surface modification
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.169946

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 µm 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 µm. Witness marks of plasticity were revealed in both the MAX and TiAl2 phases. [Display omitted] •A composite approach is tested to overcome brittleness in MAX phases.•Integrity is maintained after surface severe plastic deformation (SSPD).•Damping effect of the added TiAl2 phase prevents grain decohesion and delamination.•The composite approach enables a hardness increase up to 60% after SSPD.•Plasticity is observed in both the MAX and TiAl2 phases.