三元Pb-Sb-Sn合金的快速凝固及组织特征

实现了三元Pb-12%Sb-4%Sn和Pb-15%Sb-10%Sn合金在深过冷条件下的快速凝固,实验中获得的最大过冷度分别为65 K(0.13TE)和70 K(0.13TL)。XRD分析表明,这两种合金在实验过冷度范围内均由(Pb)固溶体、(Sb)固溶体和SbSn金属间化合物三相组成。在小过冷条件下,Pb-12%Sb-4%Sn共晶合金的三相以层片状交替分布,协同生长。随着过冷度增大,(Sb)作为初生相以小平面方式生长,且三元层片共晶组织显著细化。对于Pb-15%Sb-10%Sn合金,其凝固组织由初生相、二相共晶和三元共晶组成,初生SbSn相以具有小平面特征的枝晶方式生长。在实验基础上,对三元Pb-Sb-Sn合金的形核特征和生长规律进行了理论分析。

Exploring a Better Understanding of Rapid Growth Mechanism of Two Ternary Pb-Sb-Sn Alloys under Changing Degree of Undercooling

Aim.Pb-Sb-Sn alloys are widely employed industrially.So it is logical to explore a better understanding of their rapid growth mechanism.We now present our preliminary results of exploration on such mechanism for two liquid ternary Pb-12%Sb-4%Sn and Pb-15%Sb-10%Sn alloys,which were respectively undercooled up to 65 K(0.13 TE) and 70 K(0.13 TL).In the full paper,we explain our exploration results in some detail;in this abstract,we just add some pertinent remarks to listing the two topics of explanation.The first topic is: experimental method.In this topic,we use glass fluxing technique and silicon oil purifying method to achieve rapid solidification and use differential scanning calorimeter (DSC),X-ray diffraction(XRD) meter and scanning electronic microscope(SEM) to characterize the samples of the two alloys.The second topic is: experimental results and their analysis.The first subtopic of this topic is: the rapid solidification of Pb-12%Sb-4%Sn ternary eutectic alloy.The DSC analysis shows that the ternary eutectic reaction temperature of this alloy is 512 K,which is basically in agreement with the temperature in equilibrium phase diagram,given in Fig.1 in the full paper.Its microstructure is characterized by ternary lamellar eutectic under low undercooling condition,but it increases in fineness with increasing degree of undercooling,as shown in Fig.5.Moreover,the primary(Sb) phase nucleates and grows in a faceted manner and in priority to the other two phases in the alloy melt of high degree of undercooling.The second subtopic of the second topic is: the rapid solidification of Pb-15%Sb-10%Sn ternary alloy.Its microstructure consists of primary SbSn phase,SbSn (Pb) pseudobinary eutectic phase and SbSn (Pb) (Sb) ternary eutectic phase under changing degree of undercooling,as illustrated in Fig.9.The primary SbSn phase grows to form dendrites in a faceted manner,and its crystal grain size and interspace of dendrites decrease with increasing degree of undercooling,as shown in Fig.10.