Microstructure And Properties Of Electrolytic Titanium Eutectic Al-si Piston Alloy

In this paper, the eutectic Al-Si alloys used in pistons of automobile and motorcycle engine have been studied mainly. The eutectic Al-Si ZL108 experimental alloys are produced directly by the electrolytic low-titanium Al-based alloy ingots replacing the pure aluminum ingots, which named EZL108Ti. The microstructure, mechanical properties at room and elevated temperature as well as the wear performance of the eutectic Al-Si EZL108Ti piston alloys adding titanium by electrolysis are investigated in detail. The mechanism of grain refinement, strengthening and wear resistance of the alloys is analyzed carefully. Based on above the investigation, the application of EZL108Ti alloys in pistons of motorcycle and the stand test of experimental pistons are made. The results show that it is feasible for the electrolytic low-titanium Al-based alloys to be used directly to produce high quality pistons, this kind of EZL108Ti pistons should have good prospect of application in pistons of automobile and motorcycle engine.The microstructure of the eutectic Al-Si alloys with different titanium content adding titanium by electrolysis are analyzed and investigated comparatively for the first time. The results show that the microstructure of experimental alloys adding titanium by electrolysis is refined remarkably, when titanium content in the alloys is about 0.10%. Here, the α (Al) second dendrite arm spacing is minimum which is 16.71 μm. The long diameter, short diameter and mean diameter of the eutectic silicon particles are all minimum which are 3.28 μm, 2.29 μm and 2.69 μm respectively. The morphobgy of tntermetallic compound iron-rich phases turn from fish-bone shape to typical blunt Chinese characters shape, distributing in grain boundary or interdendrite, it is heat-stability phase at elevated temperature and helpful to improve mechanical properties of experimental alloys at elevated temperature. Comparing the microstructure of experimental alloys adding titanium by electrolysis with that adding titanium by Al-Ti master alloys, their α (Al) second dendrite arm spacing and the size of eutectic silicon particles are almost equivalent.The refinement mechanism of titanium on experimental alloys is analyzed. The...