Synthesized Phases, Microstructure and Mechanical Properties of TiAl Base and Ni₃Al Base Composite Intermetallic Compounds by Two-Step Combustion Synthesis

Abstract

ABSTRACT

TiAl base and Ni₃Al base composite intermetallic compounds were investigated by Two-step combustion synthesis process. In TiAl–Ni₃Al composite compound by the combustion synthesis, the products contain Ti₂NiAl₃ (τ₃)and TiNi₂Al (τ₄) phases, and spoil the mechanical properties of the composite compound material. Therefore, Two-step combustion synthesis of TiAl base and Ni₃Al base composite compounds were examined in compositions near the TiAl and Ni₃Al of the Ti–Ni–Al system
Elemental (Ti+Al) premixed compact was made to react by thermal explosion reaction as first step combustion synthesis. The synthesized TiAl product was grinded, and mixed with elemental Ti, Ni and Al powders again. The (TiAl+Ti+Ni+Al) mixed compact was made to react by thermal explosion reaction as second step combustion synthesis. For the products obtained, density, phase, microstructure, Vickers hardness, and compression strength were measured.
By using Two-step combustion synthesis, TiAl base and Ni₃Al base composite compounds could be fabricated. The TiAl base composite intermetallic compounds were so hard and so weak, to use for mechanical material. However Ni₃Al base composite compounds contained a few Ti component exhibited superior ductility. Therefore, it was found that the addition of Ti component into Ni₃Al is effective for improving the mechanical properties of Ni₃Al compound.