(合肥工業(yè)大學 材料科學與工程學院，合肥 230009)
摘 要: 為了探討液-液結(jié)構(gòu)轉(zhuǎn)變的可逆性及熔體狀態(tài)對凝固的影響，利用直流四電極法測量SnSb15合金熔體在三輪連續(xù)升降溫過程中的電阻率-溫度曲線。分析SnSb15合金熔體的不可逆和可逆轉(zhuǎn)變的物理內(nèi)涵，進而討論不可逆轉(zhuǎn)變對凝固影響的作用機制。結(jié)果表明：SnSb15合金熔體發(fā)生了溫度誘導(dǎo)的液-液結(jié)構(gòu)轉(zhuǎn)變，其首輪升溫過程的轉(zhuǎn)變呈不可逆性，而后續(xù)降溫及升溫過程的轉(zhuǎn)變呈可逆特征；且首輪升溫過程的不可逆液-液結(jié)構(gòu)轉(zhuǎn)變顯著影響合金的凝固行為和組織，如初生相和包晶相的形核過冷度分別增大9.7和5 ℃，凝固時間分別縮短2.5和4 s，并且凝固組織明顯細化。
關(guān)鍵字: SnSb15合金；液-液結(jié)構(gòu)轉(zhuǎn)變；可逆性；熔體狀態(tài)；凝固行為；凝固組織
（College of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China）
Abstract:In order to study the reversibility of liquid-liquid structure transition (L-LST) and the effects of melt state on solidification, the electrical resistivity-temperature curves of SnSb15 melt were measured in three heating and cooling cycles by means of DC four-probe method. The physical connotation of irreversible and reversible L-LST was analyzed, and the effects of irreversible L-LST on solidification were also discussed. The results show temperature induced L-LST occurs in SnSb15 melt. L-LST in first heating process is irreversible, but it is reversible in subsequent cooling and heating processes. Besides, irreversible L-LST can significantly affect the solidification behavior and microstructure, i.e. the undercooling degrees for primary and peritectic phase enlarge 9.7 and 5 ℃, the solidification time shortens 2.5 and 4 s, respectively. Moreover, the solidification microstructures are refined obviously.
Key words: SnSb15 alloy; liquid-liquid structure transition; reversibility; melt state; solidification behavior; solidification microstructure
