The room temperature abrasive wear behavior of three selected MAX phases, Ti₃SiC₂, solution strengthened Ti_2.7Zr_0.3SiC₂ and Cr₂AlC, is investigated by low velocity scratch testing using a diamond conical indentor with a final radius of 100 μm and a cone angle of 120° and applied loads of up to 20 N. All three materials showed a relatively low wear resistance in comparison to most engineering ceramics such as Al₂O_3, Si₃N₄ and SiC. For all three materials, the wear rate scaled more or less linearly with the applied load. The softer Ti₃SiC₂ with a hardness of 2.8 GPa showed the lowest wear resistance with extensive ploughing and grain breakout damage, both within and outside the direct wear track, in particular at the highest load. The hardest material, Ti_2.7Zr_0.3SiC₂, with a hardness of 7.3 GPa, showed a 5 times better wear resistance. The Cr₂AlC with a hardness of 4.8 GPa showed a wear resistance equal to or even better than that of the Ti_2.7Zr_0.3SiC₂. The wear mechanism depends on the applied load and the microstructure of the MAX phase materials tested. For the Ti₃SiC₂ sample, a quasi-plastic deformation behavior occurs below a point load of 10 N, resulting in grain bending, kink band formation and delamination, grain de-cohesion, as well as trans-and intra-granular fracture near the scratch groove. At this load, the Ti_2.7Zr_0.3SiC₂ and Cr₂AlC MAX samples display plastic ploughing, grain boundary cracks and material dislodgments.

Almost pure (Ti_1-xZr_x)₃SiC₂ MAX phase solid solutions with x ranging up to 0.17 were synthesized at temperatures in the range of 1450–1750 °C with reactive Spark Plasma Sintering (SPS). The zirconium partially replaces the M-element titanium of the Ti₃SiC₂ MAX phase up to x equals 0.17. The lattice parameters of the hexagonal (Ti_1-xZr_x)₃SiC₂ MAX phase are determined with X-ray diffraction using Rietveld refinement and show an anisotropic lattice expansion upon Zr insertion into Ti₃SiC₂. This observation is in very good agreement with density functional theory calculations where the deviation between the measured and calculated lattice parameter is less than 1%. The predicted elastic modulus reduction is only 4%. This behavior can be rationalized by considering the electronic structure, where only minute changes are observable as Zr is incorporated into Ti₃SiC₂. The measured nanohardness of the synthesized (Ti_1-xZr_x)₃SiC₂ MAX phase increases from 12.7 ± 1 GPa for Ti₃SiC₂ to 16.3 ± 1.1 GPa when x is raised from 0 to 0.17 due to an increasing amount of accompanying Ti_1-yZr_yC. The elastic moduli of (Ti_1-xZr_x)₃SiC₂ solid solutions measured by an ultrasonic pulse-echo method (325–354 GPa) are in good agreement with the predicted elastic moduli (357–342 GPa).