Effect Of Al-Ti-C On Microstructureand Properties Of ZL205A Aluminum Alloy

ZL205A alloy is a cast Al-Cu alloy,it is widely used in the industrial field.Obtaining fine uniform grains is an important way to improve its mechanical properties.The use of grain refiner is the most effective method in various ways of aluminum alloy grain refinement.In this paper,Al-Ti-C is used as grain refinement agent for ZL205A alloy,the effects of different Al-Ti-C addition and different holding time on the microstructure and properties of ZL205A alloy were studied,the effect of Al-Ti-C on the solidification process of ZL205A alloy was studied and the heat treatment process of ZL205A alloy was optimized.The results are as follows:(1)Al-Ti-C can effectively refine the ZL205A alloy grain.When the addition amount of Al-Ti-C alloy is 5.33%,the grain size of ZL205A alloy is the smallest,the grain size is 46 ?m and reduced 82.3%as compared to the alloy not refined.The hardness,tensile strength and elongation of the as-cast ZL205A alloy reach 70.6HV,221.9MPa and 6.3%when adding 5.33%of Al-Ti-C,which is 21.5%higher than that of Al-Ti-C,35.5%and 65.7%respectively.(2)Al-Ti-C can effectively improve the corrosion resistance of ZL205A alloy.When the amount of Al-Ti-C addition is 5.33%,the corrosion potential of the alloy in 3.5%NaCl solution increases from-0.603V to-0.544V.The corrosion resistance of the alloy is improved.(3)Al-Ti-C has a good long-term effect on the grain refinement of ZL205A alloy.Al-Ti-C has the best effect on ZL205A alloy refinement when Al-Ti-C holding time is 30min.(4)The initial crystal nucleation temperature of ZL205A alloy increases with the smaller grain size.When the refinement is not carried out,the minimum nucleation temperature of the primary crystal of ZL205A alloy is 641.6?.After adding 5.33%Al-Ti-C,TMin? was raised to 647.9?.The fastest latent heat release rate tH with the alloy grain size changes more obviouly.tH reaches a maximum after adding 5.33%Al-Ti-C.(5)The optimum heat treatment system of ZL205A alloy is:530?/12h,170?/6h.In this heat treatment system,the hardness,tensile strength and elongation of ZL205A alloy are 164.8HV,485.4MPa and 5.3%.