王一川， 傅恒志， 周 廉
(西北工業(yè)大學(xué) 凝固技術(shù)國家重點(diǎn)實(shí)驗(yàn)室， 西安 710072)
摘 要: 采用雙熱電偶法分別測得不同熔體處理A357合金的枝晶搭接點(diǎn)， 進(jìn)而通過熱分析法分別計(jì)算出枝晶搭接點(diǎn)的固相體積分?jǐn)?shù)fcohs。 結(jié)果表明， 冷卻速率和晶粒細(xì)化處理對fcohs的增大有較大影響； 而變質(zhì)劑(Sr)對fcohs值的影響不明顯。 分析表明， 冷卻速率的提高以及晶粒細(xì)化劑的加入細(xì)化了晶粒和延緩枝晶的生長， 從而提高fcohs， 而Sr的加入只改變Si的形態(tài)， 對fcohs的影響不大。
關(guān)鍵字: A357合金； 枝晶搭接點(diǎn)； 雙熱電偶； 冷卻速率； 熔體處理
dendrite coherency of A357 alloys
WANG Yi-chuan, FU Heng-zhi, ZHOU Lian
（State Key Laboratory of Solidification Processing,
Northwestern Polytechnical University, Xi'an 710072, China）
Abstract: The dendrite coherency point of A357 alloy was determined after melt-treatment by double-thermo-couple, and the solid volume fraction of coherency (fcohs)was calculated by thermal analysis. The effects of adding grain refiner Sr to the melt to modify the eutectic and the cooling rate on the increase of fcohs were investigated. The results show that the cooling rate and the addition of grain refiner significantly increase the solid volume fraction of coherency of the alloys, but the modification (Sr) has little effect on fcohs. The increase of cooling rate and the addition of grain refiner fine the grain and postpone the formation and growth of dendrite. The addition of Sr changes the morphology of Si, but has little effect on fcohs.
Key words: A357 alloy; dendrite coherency point; double-thermocouple; cooling rate; melt treatment
