摘要:
通过金相显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等对ZnAl10Cu2合金的铸态显微结构和相结构进行了观察和分析,并对其组织的形成机制进行了研究.研究表明:铸态ZnAl10Cu2合金的凝固组织由初生枝晶α1及其外围的棒状共晶(α2+β)组成,在随后的冷却过程中初生α1相和共晶组织中α2相均发生共析反应,得到层片状共析组织(α+η),而在室温时效中未完全转变的α1相和α2相均发生不连续沉淀形成粒状沉淀组织,其中初生α1相,为富Al相,是Zn在Al中形成的固溶体,属于强化相,晶体结构为面心立方,β为富Zn相,晶体结构为密排六方.
Abstract:
The as-cast microstructure and phase structure of ZnAl10Cu2 alloy were observed and analyzed by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),and X-ray diffraction(XRD).The formation mechanism of the structures was also studied.It is shown that the solidification of cast ZnAl10Cu2 alloy is consisted of primary α1 dendrites and rod-like eutectic(α2 + β) surrounding primary α1 dendrites.There occur eutectoid reactions in primary α1 phase and α2 phase in the eutectic structure during the subsequent cooling process,and lamellar(α + η) eutectoid organization forms.The retained α1 and α2 phase precipitate discontinuously and form granular precipitates in room temperature aging.The primary α1 is the Al-rich(Al forms solid solution with Zn) and strengthening phase,with the crystal structure of a face-centered cubic lattice.And for β,the crystal structure of the Zn-rich phase is a hexagonal lattice.
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