Compressive Behavior of Ti₃AlC₂ and Ti₃Al_0.8Sn_0.2C₂ MAX Phases at Room Temperature

In this study, we report on the compressive behavior of Ti₃AlC₂ and Ti₃Al_0.8Sn_0.2C₂ MAX phases at room temperature. We found that these two phases could be classified as Kinking Nonlinear Elastic (KNE) solids. The cyclic compressive stress–strain loops for Ti₃AlC₂ and Ti₃Al_0.8Sn_0.2C₂ are typical hysteretic and fully reversible. At failure, both compositions fracture in shear with maximum stresses of 545 MPa for Ti₃AlC₂ and 839 MPa for Ti₃Al_0.8Sn_0.2C₂. Consequently, the macroshear stresses for failure, τ_c, are 185 MPa and 242 MPa for Ti₃AlC₂ and Ti₃Al_0.8Sn_0.2C₂, respectively. In addition to the grain size effects, the presence of a ductile Ti_xAl_y intermetallic distributed in the grain boundaries plays an important role in the enhancement of the ultimate compressive and macroshear stresses for Ti₃Al_0.8Sn_0.2C₂. SEM observations reveal that these two MAX phases exhibit crack deflections, intragranular fractures, kink band formation and delaminations, grain push-in and pull-out.