AlSiCuMgNi piston composites reinforced with in-situ TiB2 particles were fabricated by mixing salts reaction process successfully. Microstructures of the composites were observed by mean of scanning electron microscope (SEM) and transmission electron microscope (TEM). X-ray diffraction (XRD) was used to identify the phases in the composites. TiB2 reinforcement grows in equiaxed or near equiaxed shape and the interfaces between reinforcements and matrix are clear. Compared with the matrix alloys, the composites show an obvious aging peak and an incubation time in the hardness. The aging is accelerated in the composites reinforced with TiB2. At room temperature, the ultimate tensile strength (UTS) of the composites increases as the percentage of TiB2 reinforcement increases. When the temperature is beyond 250 degrees C, the ultimate tensile strength of the piston composites decreases sharply. The fracture surfaces of the piston composites are analyzed. (c) 2006 Springer Science + Business Media, Inc.