The piston is made of low-plastic cast aluminum alloy as the matrix material, and its composition contains mixed rare earth elements rich in arsenic and trace metal elements such as Sn, Pb, Zn, Cr and Ti, which account for 0.8~1.4% of the alloy. Piston in high temperature, high pressure, high speed, poor lubrication conditions. Piston direct contact with high temperature gas, instantaneous temperature up to 2500K above, therefore, serious heat, and heat dissipation conditions are very poor, so the piston working temperature is very high, the top of the 600~700K, and the temperature distribution is not uniform; Piston top under the gas pressure is very large, especially the work stroke pressure is the largest, gasoline engine as high as 3~5MPa, diesel engine as high as 6~9MPa, which makes the piston impact, and bear the lateral pressure; Piston in the cylinder at a high speed (8~12m/s) reciprocating motion, and the speed is constantly changing, which produces a large inertial force, so that the piston is subjected to a large additional load. Working in these harsh conditions, the piston will deform and accelerate wear, as well as generate additional load and thermal stress, and suffer from the chemical corrosion of the gas.