K_2TiF_6细化处理对高强度铸造铝铜合金组织和性能的影响

Influences of K2TiF6 Refinement on Microstructure and Mechanical Properties of High Strength Al-Cu Casting Alloy

研究了K2TiF6细化处理和热处理对高强度铸造铝合金组织和力学性能的影响。结果表明,高强度铸造铝铜合金的未细化处理的铸态组织为α(Al)固溶体和在晶界分布的θ(Al2Cu)及T(Al12CuMn2)相,α(Al)相组织粗大。加入一定量的K2TiF6可以细化试验材料铸态组织,使粗大的α(Al)枝晶变小,减小α枝晶尺寸,改善力学性能。加入1.0%K2TiF6细化处理细化效果较好,530℃固溶,175℃时效处理,获得的拉伸强度最高为386MPa。不同含量的K2TiF6细化处理的试样,固溶及时效处理后其组织均为α(Al)固溶体及其晶内弥散分布的θ相和T相,晶界处残留有未完全溶解的T相,组织中α(Al)晶界出现无析出带。

The effects of K2TiF6 refinement and heat treatment on the microstructure and mechanical properties of high strength Al-Cu casting alloy were investigated.The results show that the as-cast microstructure of un-refinement is coarse α（Al） solid solution phase,and θ（Al2Cu） and T（Al12CuMn2） phase which distribute in the bound of the grain.A certain amount of K2TiF6 addition can refine as-cast microstructure of high strength Al-Cu casting alloy and change α phase from coarse α phase to fine α phase and decrease dendrite crystal size,improve mechanical properties.The refinement effect is better when adding K2TiF6 content 1.0% and the highest tensile strength is 386 MPa after solution treatment at 530℃ and aging treatment at 175℃.The microstructure of K2TiF6 refinement test materials is made of α（Al） phase and a lot of dispersed secondary θ and T phase which distribute in the α（Al） phase and retained T（Al12CuMn2） phase in the bound of grain,and the clear precipitate-free zones surrounding the α（Al） phase is appeared after solution and aging.