The Influence Of Rare-earth Ce On Microstructure And Mechanical Properties Of Squeeze Casting ZA27 Alloy

The influence of rare-earth Ce on microstructure and mechanical properties of squeeze casting ZA27 alloy was studied in this paper. ZA27 cup-shaped squeeze casting with content of Ce 0%, 0.15%, 0.30%, 0.45% and 0.60% was prepared under the processing parameters of specific pressure 320MPa, mould temperature 180℃～220℃, pouring temperature 650℃, pressure time 30s and pressure holding time 45s. The results show that the mechanical properties of cup-shaped ZA27 casting can be attained as follows: tensile strengthσ_b≥420MPa, elongationδ₅≥5.5%, hardness HB≥124. Rare-earth Ce can significantly improve the combination properties of ZA27 cup-shaped squeeze casting alloy, e.g. tensile strength and hardness are increased apparently.Through deterioration, purification and micro alloy function, rare-earth Ce have refined microstructure of squeeze casting ZA27 alloy. The microstructure have been obviously improved when Ce content is 0.15%. Irregular and white compounds have been generated around crystal grain edge and crystal boundary when Ce content is more then 0.30%. The compound contains elements of Zn, Al, Cu, Ce and Mg by using the electron probe,α,βand eutectic phases have been detectde by using line scanning. Few Ce element has been found inside these phases. And main amount of rare earth Ce was found within the compound in the ZA27 alloy.The influence of heat treatment on the microstructure and mechanical properties has been researched in this paper. Heat treatment can uniform the structure of bar-shaped ZA27, and thus better combination properties after 320℃×8h water quench+100×6h aging are obtained. 320℃×8h water quench+ 150℃×6h aging may improve the elogation of alloy.