Creep properties of nickel aluminide composite materials reinforced with SiC particulates

Abstract

Nickel aluminide intermetallic is being considered as a structural component for high temperature applications. A large number of investigations have been reported on the mechanical properties of nickel aluminides but very little has been reported on the mechanical properties of nickel aluminides reinforced with SiC particulates. An investigation of the creep properties of SiC particulate reinforced nickel aluminide composite is presented. The SiC particles were about 15–30μm in diameter. The objective of the investigation was to understand the effectiveness of the SiC particulate reinforcements in improving creep properties and to correlate the creep strain rate to the material microstructure. The composite material consisted of Ni–50wt.% Al matrix reinforced with 10, 20, and 30vol.% of SiC particulates. The material was fabricated using a solid-state powder metallurgy technique. Uniaxial compression test was performed on NiAl and reinforced composites prior to the creep test to determine the elastic properties of the creep samples. Constant compressive load creep tests were performed at 950°C on the un-reinforced nickel aluminide and the reinforced composite samples. The steady-state compressive creep strain rate ε˙ss of composite was found less than ε˙ss for the un-reinforced nickel aluminide. The creep strain rate decreased with increasing volume fraction of reinforcement phase. Micro-indentation tests were also performed at room temperature to determine matrix/reinforcement interfacial strength. The hardness results and microstructural images indicate a strong NiAl/SiC interface.