| Zinc aluminum alloy is widely used in automobile,instrument,electronic equipment and other manufacturing fields because of its excellent fluidity,castability and mechanical properties.At present,the most widely used alloy in industry is YZZn Al4(ZX01)alloy with 4wt.%Al.Since the price of zinc ingot is about 1.3 times of aluminum ingot,the increase of Al content in Zn-Al alloy will effectively reduce the production cost of the alloy and rationally utilize the resources.In this paper,ZX01 is used as a reference alloy.The melting point,fluidity,microstructure and mechanical propertie of zinc alloy was characteristiced.On the basis of good performance and mechanical performance,the low cost die casting Zn-6Al alloy was developed.The research results have important reference value for the industrial production of high-quality and low-cost Zn-Al alloy,and actively promote the technological progress of die casting industry.The effects of Al content on physical properties,microstructure morphology and mechanical properties of Zn-Al alloy were studied when the Al content varied from 4 to 10 wt.%Al.The results show that the melting point of Zn-Al alloy increases with the increase of Al content,and the primary β-Al phase increases and coarsenes with the increase of Al content,which hinders the flow of metal melt and reduces the fluidity of the alloy.With the increase of primary β-Al phase area fraction,the hardness,tensile strength and yield strength of Zn-Al alloy are improved.When Al content is 6wt.%,Zn-Al alloy has good fluidity and better comprehensive mechanical properties.The effect of casting process on the microstructure and mechanical properties of Zn-6Al alloy was studied.The results show that primary β-Al in the microstructure of Zn-6Al alloy is distributed uniformly and in large quantity in the matrix when the melting temperature is 390℃ ～500℃ and430℃.After melting at 430℃ and holding for 15 min,the primary phase of the Zn-6Al alloy prepared at room temperature is spherical and granular,without obvious dendrite characteristics.The primary phase is moderate in size and evenly distributed in the matrix,and the overall mechanical properties of the alloy are the best.The tensile fracture morphology of Zn-6Al alloy prepared by this process shows a small cleavage plane and a large number of tear ridges,and dot dimples are distributed on the fracture surface,indicating that the alloy has good toughness.The microstructure and mechanical properties of Zn-6Al alloy modified at 600℃ by zn-6Al alloy modified at 430℃ were studied.The results show that when the amount of Al-5Ti-B is 0.5wt.% and the mass ratio of high temperature modified melt to low temperature melt is 2:3,the comprehensive mechanical properties of Zn-6Al alloy are the best.When the mass ratio of high and low temperature melt is 2:3 and the amount of Al-5Ti-B modifier is 0.75 wt.%,the primary phase in the microstructure of Zn-6Al alloy is smaller,more and evenly distributed in the matrix,and the comprehensive mechanical properties of Zn-6Al alloy are the best.The microstructure genetic characteristics of the modified Zn-6Al alloy were studied.The results show that the remelting temperature of the modified Zn-6Al alloy with Al-5Ti-B is better to be controlled below 450℃in order to keep the modification effect of the alloy.The tensile strength and yield strength of the modified alloy are higher than 300 MPa and250MPa respectively after remelting at 430℃and heat preservation within30 min,which fully meet the design requirements of the project.In the diecasting production of Zn-6Al alloy,the temperature of the metal mold should be strictly controlled within 150℃ to ensure the mechanical properties of the modified alloy die-casting products.When the remelting temperature is 430℃,as long as the melt holding time is less than 30 min,the comprehensive mechanical properties of the Zn-6Al alloy solidified in room temperature metal mold could meet the performance requirements. |
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