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The short NiTi fiber-reinforced NiTi/Al6061-SiC composite was recently developed through the U.S. Army SBIR Phase-II program [1]. The objectives of this project are to use short NiTi fiber reinforcement to induce compressive stress through shape memory effect, to use silicon carbide (SiC) particulate reinforcement to enhance the mechanical properties of the aluminum matrix, to gain fundamental knowledge of short NiTi fiber-reinforced aluminum matrix composite, and eventually to improve fatigue resistance, impact damage tolerance and fracture toughness of the composite. The fatigue life, damage and fracture behavior of TiNi/Al6061-SiC, TiNi/Al6061, Al6061-SiC composites as well as monolithic Al6061 alloy were investigated under fully reversed cyclic loading. It was found that fatigue life of NiTi/Al6061-SiC composite, in term of the cycles, increased by two orders of magnitude, compared to monolithic Al6061 alloy

A composite of an aluminum matrix reinforced by short TiNi shape memory alloy (SMA) fibers was fabricated. The processing and thermomechanical behaviors of the composite TiNi/Al6061 were investigated experimentally and analytically. Optimal hot-pressing conditions of TiNi/Al6061 processing were identified. The shape memory effect (SME) was activated by prestraining the composite at the temperature between Ms and As, followed by heating up to Af. SME on mechanical properties, such as microhardness, yield stresses of the composite, were investigated. A computational model for the strengthening mechanism of the short fiber metal matrix composite was utilized to analyze SME on yield stress of the composite. Yield stress of the composite as a function of prestrain was predicted numerically and verified experimentally.