Mechanism And Effect Of Electric Pulse On The Microstructures Of Silicon Phase Of Eutectic Al-Si Piston Alloy

Al-Si piston alloy has been widely used because of its low density, good high strength, good wear resistance. However, the feature of Si phase direct impact on the mechanical properties of Al-Si piston alloy .including shape, number, size and distribution. Therefore, it could improve the mechanical properties of Al-Si piston alloy,by improving the feature of Si phase.the electrical pulse has been used during manufacture of the Al-Si piston alloy in this paper.The rule on improving feature of Si phase in the Al-Si piston alloy solidification structure has been studied at various electrical pulses parameters, and the influence also was analysised.In addition, and the rule and mechanism on the influence of Si phase at.various solution-aging parameters has been investigated, too. Finally, the experimental results applied to practical production process.The result shows that it the best feature of Si phase and Si phase diffuse distributing inα-Al when using pulse voltage 1000 V, pulse frequency 3 Hz. And the microhardness value could reach 169 HV, that is 1.23 times of the Al-Si piston alloy without electrical pulses. The other hands,Primary silicon edges were smooth after solution-aging, and solution-aging time would be shorten by electrical pulses. the maximum microhardness of Al-Si piston alloy was 169 HV when solid solution time was 2 h and aging time was 4 h with. Finally, The eutectic silicon in the cast with electrical pulses Al-Si piston alloys characterizes as short-rod shaped instead of needle-like in die casing Al-Si piston alloys, It helped to weaken the harmful effect of needle-like eutectic silicon on the alloy, to strengthen the tensile properties in high temperture, and to premote formation of Al8Si6Mg3Fe, at 300℃the tensile propertie could reach 230Mpa when using pulse voltage 1000 V, pulse frequency 3 Hz., that was 1.25 times of the Al-Si piston alloy without electrical pulses.