The Study Of TINI Particles Reinforced Aluminum Matrix Composites Prepared By Friction Stir Processing

Shape memory alloys (SMA) have the ability of recovering to the original shape being deformed. This unique shape memory (SM) behavior is resulted from a kind of thermo-elastic phase change from the low temperature martensite phase to the high temperature austenite phase. The property of showing shape memory effect provided the SMAs with a wide application as smart materials. It is a promising way to introduce SMAs into Al alloys to prepare special metal-matrix composite possess SM effect with low density, high strength.In order to obtain the composites, a new array-drilling particle preset imbed method was developed for friction stir processing (FSP). In this study, commercial 6061-T651 aluminum alloy was chosen as the matrix and TiNi shape memory alloy particles (TiNip) were adopted as the reinforcement and the TiNip reinforced Al composites was fabricated.The mechanical properties of the composites before and after T6 heat treatment were tested. The interface between the TiNip reinforcement and Al alloy matrix was observed by microscope and scanning electron microscopy. X-ray diffractometer was used for phase analysis. Shape memory effects of the composite material were studied by differential scanning calorimetry (DSC) and thermal dilatometer (DIL).The followed results were obtained: TiNi particles are homogeneously distributed in the matrix. The TiNip/Al interface is clear and no interfacial products was found. The total volume of TiNip is about 10%. The new TiNip/Al composite material remained the shape memory characteristic. However, due to the lower volume fraction of TiNip, the shape memory effect of the composite is corresponding decrease. After moderate cold-rolling, the composite exhibits lower dilatability compared with the aluminum alloy inside a certain temperature range. After T6 heat treatment, the room-temperature tensile strength of TiNip/Al composite slightly beyond the base metal.