Investigations on the crystallographic stacking disordering and properties of novel Ga-containing in-plane chemically ordered (Cr2/3R1/3)2GaC (R=Y, Tb - Lu) i-MAX phases

• Published in: Acta materialia Vol. 277; p. 120213
• Main Authors: Chong, He, Wang, Chaobo, Guo, Hongyun, Sun, Shuli, Gong, Weijiang, Fu, Xiaoxiao, Huang, Xiaoxu, Ma, Shangyi, Liu, Gang, Wang, Qiang, Cui, Weibin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.09.2024
• Subjects: High-density sliding; i-MAX phase; Mechanical properties; Rare-earth; Mechanical properties; i-MAX phase; Rare-earth; High-density sliding
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2024.120213

Eight novel transition metal carbides, nanolaminated (Cr2/3R1/3)2GaC (R=Y, Tb, Dy, Ho, Er, Tm, Yb and Lu) with R in-plane chemical ordered occupation, have been synthesized with mainly Cmcm orthorhombic structure and monotonously decreased lattice parameters due to lanthanide contraction. Stacking disorderings and high-density slidings within c plane have been observed. Two characteristic in-plane sliding, along [100] or [1¯30]o directions have been analyzed with former one leading into the structural evolution between Cmcm and C2/c symmetry. Such an atomic scale co-existence of Cmcm and C2/c structures is explained by more negative charge for Ga and anisotropic bonding with Ga compared with A=Al case. Thus, the Vickers hardness, fracture strength and increased wear depth are reduced in representative (Cr2/3Lu1/3)2GaC i-MAX bulk compared with the (Cr2/3Lu1/3)2AlC counterpart. [Display omitted]