Sn-Pb合金微粒的制备和微结构

采用均匀颗粒成型法(Uniform Droplet Spray—UDS)制备出Sn—5％Pb合金微粒，颗粒的粒度分布均匀，性能一致．用非绝热容量法测量了在N2—2％H2气氛下Sn—5％Pb微粒的焓，井分析了颗粒的显微结构，结果表明：Sn—5％Pb微粒具有较大的过冷度和亚稳态结构．

Microstructure of Sn-Pb droplets prepared by uniform droplet spray

Sn-5% Pb droplets were prepared by using Uniform Droplet Spray (UDS). The droplets have the same size and the thermodynamic property, which is superior to the conventional spray forming processes (such as gas atomization) and has high potential applications. The enthalpy of Sn-5% Pb droplets traveling in N2-2% H2 was measured as a function of flight distance by a non-adiabatic calorimetric technique. The microstructure of the droplets was also examined under the optical microscope. The enthalpy released by the droplets in the calorimeter increased abruptly up to a certain flight distance. Sn-5%Pb droplets prepared by using UDS process traveling in N2-2%H2 had large undercooling and metastable structure. The formation of the supersaturated solid solution in the droplets quenched before nucleation was verified metallographically and by calculations based on a thermodynamic model.