深过冷Cu-20wt%Pb亚偏晶合金的凝固行为  

Solidification Behavior of Undercooled Cu-20wt%Pb Hypomonotectic Alloy

作　　者：张忠明[1] 孙万里[1] 徐春杰[1] 郭学锋[1] 

机构地区：[1]西安理工大学材料科学与工程学院,陕西西安710048

出　　处：《西安理工大学学报》2005年第2期118-121,共4页Journal of Xi'an University of Technology

基　　金：陕西省自然科学研究计划项目(2003E1);陕西省教育厅专项科研计划项目(03JK132)

摘　　要：采用熔融玻璃净化和循环过热相结合的方法,使Cu20wt%Pb亚偏晶合金获得了208K的深过冷,在宽过冷范围内研究了CuPb亚偏晶合金的组织演化规律。结果表明,过冷合金熔体初生相为α(Cu),在0～146K的过冷度范围内,均有两次再辉现象;在183～208K的过冷范围内,只出现一次再辉。当ΔT≤98K时,合金凝固组织为粗大枝晶α+枝晶间Pb相;当116K≤ΔT≤146K时,凝固组织已无明显的枝晶形貌,组织由细密α基体+细小的Pb颗粒组成;当ΔT≥183K时,凝固组织与中等过冷度下的组织相似,只是Pb相更细小,分布更均匀。当ΔT≥133K时试样出现裂纹。Solidification behavior of undercooled Cu-20wt%Pb hypomonotectic alloy was studied by employing the complex method of molten glass denucleating combined with thermal cycling so as to obtain high undercooling up to 208 K in Cu-20wt%Pb hypomonotectic alloy melt.The results indicate that the undercooling alloy melting primary phase is α(Cu),and that twice recalescence occurred in Cu-20wt%Pb hypomonotectic alloy melts in the range of 0K to 146 K,and the second recalescence was smaller than the first recalescence,whereas only once recalesence was observed for those melts with undercoolings in the range of 183 K to 208 K.When the undercooling was less than 98 K,the microstructures were composed of coarse dendrites and interdendritic lead phase. With the undercooling increasing up to the range of 116 K to 146 K, the morphology of dendrites grains in the Cu-20wt%Pb hypomonotectic alloy became unapparent,the microstructures were composed of dense α(Cu) substrate and refined Pb grains; When the undercooling exceeded 183 K,the microstructures were similar with those of the alloy at moderate undercoolings,whereas Pb phase became much smaller and distributed more even.Hot-cracks existed in the alloy when the undercooling exceeding 133 K.

关 键 词：深过冷 再辉 Cu—Pb亚偏晶合金 组织演化 

分 类 号：TG111.4[金属学及工艺—物理冶金]