【摘 要】
：
The microstructure and microhardness of Sn-3.5%Ag solders were explored in the cooling rate ranging from 0.08 to 104 K/s.Under rapid cooling condition, the stro
【机 构】
：
College of Materials Science and Engineering
论文部分内容阅读
The microstructure and microhardness of Sn-3.5%Ag solders were explored in the cooling rate ranging from 0.08 to 104 K/s.Under rapid cooling condition, the strong kinetic undercooling effect leads to the actual solidification process starting at the temperature lower than the equilibrium eutectic point, and the actual metastable eutectic point shifts to the higher Ag concentration. Hence, the higher the applied cooling rate is, the more the volume fraction of primaryβ-Sn crystal forms. At the same time, the separation of primaryβ-Sn crystal favors restraining the formation of bulk Ag3Sn intermetallic compounds (IMCs) in solder due to the mismatch crystalline orientation relationship, those Ag3Sn phase separating through the eutectic reaction could hardly cling to the primary β-Sn crystal and grow up. Additionally, the Vickers hardness test shows that fineβ-Sn and spherical Ag3Sn phase in the rapidly solidified alloy strongly improves the microhardness of the Sn-3.5%Ag solder.
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