Fabrication of Al‐Added TiN Materials by the Combination of Double Self‐Propagating High‐Temperature Synthesis and Pulsed Electric‐Current Pressure Sintering

Crystalline phases of Al‐added TiN, denoted as (Ti 1− x Al x )N y (0≤ x ≤0.10, 0.8< y <1.0), prepared from a mixture of Ti and Al powders by self‐propagating high‐temperature synthesis (SHS) in a nitrogen atmosphere, have been investigated. By repeating SHS twice, in the region of 0.0< x ≤0.02 cubic (Ti 1− x Al x )N y solid solutions, and in the region of 0.02< x ≤0.10 composites consisting of (Ti 1− x Al x )N y and hexagonal Ti 2 AlN were formed. After powder characterization, they were consolidated to dense materials (>97% of theoretical) by pulsed electric‐current pressure sintering. With increasing Al addition, the optimum sintering temperatures were lowered, followed by reduction of grain size. Their mechanical properties, that is, three‐point bending strength σ b , Vickers hardness H v , and fracture toughness K I C were evaluated as a function of Al content.