Influence of chemical composition on the room temperature plasticity of C 15 Ca-Al-Mg Laves phases

M Freund and ZC Xie and PL Sun and L Berners and J Spille and HX Wang and C Thomas and M Feuerbacher and M Lipinska-Chwalek and J Mayer and S Korte-Kerzel, ACTA MATERIALIA, 276, 120124 (2024).

DOI: 10.1016/j.actamat.2024.120124

The influence of chemical composition changes on the room temperature mechanical properties in the binary Ca 33 Al 67 C 15 CaAl 2 Laves phase were investigated in two ternary alloys with off-stoichiometric compositions with 5.7 at.% Mg substitution (Ca 33 Al 61 Mg 6 ) and 10.8 at.% Mg and 3.0 at.% Ca substitution (Ca 36 Al 53 Mg 11 ) and compared to the stoichiometric (Ca 33 Al 67 ) composition. Cubic Ca-Al-Mg Laves phases with multiple crystallographic orientations were characterised and deformed using nanoindentation. The hardness and indentation modulus were measured to be 4.1 +/- 0.3 GPa and 71.3 +/- 1.5 GPa for Ca 36 Al 53 Mg 11 , 4.6 +/- 0.2 GPa and 80.4 +/- 3.8 GPa for Ca 33 Al 61 Mg 6 and 4.9 +/- 0.3 GPa and 85.5 +/- 4.0 GPa for Ca 33 Al 67 , taken from our previous study, respectively. The resulting surface traces as well as slip and crack planes, were distinguished on the indentation surfaces, revealing the activation of several different 11n slip systems, as further confirmed by conventional transmission electron microscopic observations. Additionally, the deformation mechanisms and corresponding energy barriers of activated slip systems were evaluated by atomistic simulations.

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