Nanolaminated ternary carbide (MAX phase) materials for high temperature applications

There is a clear need for high-strength (>= 300 MPa), thermally stable, conductive materials that are also thermal shock resistant. Some MAX phases - ternary nano-laminated carbides and nitrides - are reported to fulfil all these requirements and can be considered as potential structural materials for high-temperature applications. In this work, a set of quaternary (M,M')AX phase materials based on the Nb.Al.C system were synthesized by reactive hot pressing, starting from M-hydride powders. The possibility to substitute Nb with at least 10 at% of other M elements (M' = Ti, Zr, Hf and Ta) in the crystal lattice was investigated. The crystal structure of the produced solid solutions was studied by X-ray diffraction and the lattice parameters were calculated by Rietveld refinement. The material behaviour in an inert atmosphere was tested by measuring the elastic properties - Young's Modulus and internal friction - as a function of temperature up to 1500 degrees C, and the effect of the substitution on the room temperature flexural strength was assessed.