【摘要】 采用熔铸法制备了一种模具用高硬度Zn-Al-Cu（ZAC）合金，并探究了不同退火工艺对其组织演变及力学性能的影响。采用X射线衍射（XRD）、扫描电镜（SEM）、能谱仪（EDS）、室温拉伸/压缩试验和布氏硬度计等表征了合金的显微组织、拉伸断口形貌、微区成分和力学性能。结果表明：铸态ZAC合金的组织相结构复杂，包含初生β枝晶、层片状（η+β）/（η+α）共晶共析组织、沿晶ε（CuZn₅）相和团聚状θ（CuAl₂）相等；随着退火温度从290℃升高至380℃（退火时间为3 h）或保温时间从1 h延长至7 h（退火温度为320℃）,合金中均匀分布的β相和ε相增多，合金组织由粗大枝晶及层片状组织转变为均匀细小的粒状组织，合金的布氏硬度和抗压强度先升后降，断后伸长率升高；退火过程中含铜ε相的增多及均匀化是合金获得高硬度、高强度且塑性不被削弱的主要原因。铸态ZAC合金经（320～350℃）×3 h退火后达到较佳的性能匹配，布氏硬度达158.80 HBW,抗压强度达918.55 MPa,断后伸长率达4.6%。更多还原

【Abstract】 A high-hardness Zn-Al-Cu（ZAC） alloy for molds was prepared by melt-casting method, and the effects of different annealing processes on its microstructure evolution and mechanical properties were investigated. Microstructure, tensile fracture morphology, micro area composition and mechanical properties of the alloy were characterized by means of X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） analysis, room temperature tensile/compression test and Brinell hardness tester. The results show that the microstructure of the as cast ZAC alloy is complex, including primary β dendrite, lamellar（η+β）/（η+α） eutectic eutectoid structure, intergranular ε（CuZn₅） phase and agglomerated θ（CuAl₂） phase. With the increase of annealing temperature from 290 ℃ to 380 ℃（annealing time is 3 h） or holding time from 1 h to 7 h（annealing temperature is 320 ℃）, the number of uniformly distributed β-phase and ε-phase of the alloy increases, the microstructure of the alloy changes from coarse dendrite and lamellar structure to uniform and fine granular structure, the Brinell hardness and compressive strength of the alloy increase first and then decrease, and the elongation increases. The increase and homogenization of copper-containing ε phase during annealing process are the main reasons of the alloy for obtaining high hardness, high strength and no decrease in plasticity. After annealing at（320-350 ℃） for 3 h, the as cast ZAC alloy achieves a better performance match, the Brinell hardness reaches 158.80 HBW, the compressive strength reaches 918.55 MPa, and the elongation reaches 4.6%.更多还原