52 m长落管Ag-Ge合金的微重力凝固行为

利用52m长落管装置进行了Ag-15%Ge(质量分数)亚共晶和Ag-21%Ge(质量分数)过共晶合金微重力试验,分析了凝固后合金球体的显微组织,并和常规凝固条件下的同成分合金组织进行了比较.结果表明,落管实验能使合金获得较大的过冷度,使Ag-15%Ge(质量分数)亚共晶合金Ag初生回溶体相明显细化,枝晶特征消失并转变为细小不规则块状或近似球形;使Ag-21%Ge(质量分数)过共晶合金中Ge初生相组织细化、数量增多,但并不改变小平面晶体Ge相的侧面生长机制.

Solidification of Ag - Ge Alloys under Microgravity in 52 m Drop Tube

Ag-15%Ge(weight percent) hypoeutectic and Ag-21%Ge(weight percent) hypereutectic alloys are solidified under microgravity in a 52 m drop tube.The microstructure of the solidified alloys are analyzed and compared with that of the conventional solidified alloys with the same composition.It reveals that large undercooling of the alloys can be obtained after solidification in drop tube,with microstructure significantly refined.For the hypoeutectic alloys,primary Ag phase transform from dendrite to unregular or sphere-like particles.For the hypereutectic alloys,the primary Ge phase is refined,with its number greatly increased.However,the primary Ge phase still grows through the lateral growth mechanism.