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通过研究Sn-6Bi合金熔体电阻率随温度的变化规律,发现在不同的温度区间合金发生了两种不同类型的液液结构转变,即高温阶段(890～1095℃)不可逆转变和低温阶段(645℃)的可逆液液结构转变。分析认为可逆的液液结构转变是由四面体结构的Sn-Sn共价键团簇的打破和重聚引起的,而不可逆液液结构转变是由(Bi)n原子集团、亚稳态的Sn原子团簇引起的。根据这一结果进行凝固试验,发现当熔体经历过温度诱导结构转变后会使凝固过冷度增大,凝固时间延长,凝固过程中释放的凝固潜热略微减少,凝固组织明显细化。
Through the study of the variation of melt resistivity of Sn-6Bi alloy with temperature, it is found that there are two different types of liquid-liquid structure transitions in the alloy at different temperature intervals, ie irreversible transformation in the high temperature stage (890 ~ 1095 ℃) and low temperature stage 645 ℃) reversible liquid-liquid structure change. It is considered that the reversible liquid-liquid structure transition is caused by the breaking and reaggregating of Sn-Sn covalent clusters with tetrahedral structure, whereas the irreversible liquid-liquid structure transition is caused by the (Bi) n atomic group, the metastable Sn Caused by atomic clusters. According to the results of the solidification test, it is found that when the melt undergoes temperature-induced structural transformation, the degree of undercooling increases, the solidification time prolongs, the latent heat of solidification released during the solidification decreases slightly, and the solidified structure is obviously refined.