Mechanical behaviors, lattice thermal conductivity and vibrational properties of a new MAX phase Lu2SnC

Abstract In this work we examine, via density functional theory (DFT), material properties of the recently synthesized Lu-based MAX phase Lu 2 SnC and facilitate comparison with the Sn-containing MAX phases M 2 SnC (where M = Ti, Zr, Hf and Nb). Structural, elastic, mechanical, thermal and vibrational properties of Lu 2 SnC are calculated for the first time. In regard to the elastic properties and the mechanical behavior, it is predicted that Lu 2 SnC is softer and more easily machinable than the other examined M 2 SnC phases. All the M 2 SnC phases, including Lu 2 SnC, are mechanically and dynamically stable and elastically anisotropic. Calculated acoustic Debye temperature is lowest for Lu 2 SnC among the examined M 2 SnC phases. Clarke's and Slack's approximation models are employed to estimate the minimum and lattice thermal conductivities for all the 211 MAX compounds under study. Lu 2 SnC should have candidacy for thermal barrier coating (TBC) material because of its high thermal shock resistance, low minimum thermal conductivity, high melting point and characteristically good oxidation resistance. Ab-initio calculations presented in this study should be complementary to future experimental and theoretical work which can lead to further insights.