急冷条件下Ni—Pb偏晶合金的相分离研究.pdfVIP

学兔兔 Aug．2009 铸 造 VO1．58 NO．8 FOUNDRY ·775· 急冷条件下Ni—Pb偏晶合金的相分离研究 徐锦锋，范于芳，陈 娓，翟秋亚 (西安理工大学材料科学与工程学院，陕西西安710048) 摘要：采用单辊法实现了Ni．Pb偏晶合金的快速凝固，分别制备出直径40-400 m的合金粒子和宽约4nml、厚30-50 m 的合金条带。在急冷快速凝固条件下，Ni-8％Pb亚偏晶合金由Ni和富Pb相组成。Ni以枝晶方式生长，富Pb相分布于枝 晶间隙。随着冷却速率的增大，凝固组织显著细化，晶体形态经历由粗大枝晶向细小等轴晶的转变。在快速凝固过程 中，Ni．60％Pb过偏晶合金的液相分离在很大程度上被抑制，合金粒子和条带均可获得均匀弥散的快速凝固组织。在冷 却速率相近的条件下，合金粒子和条带的凝固组织与晶粒尺寸具有相似相近性，冷却速率是决定合金凝固组织的本征 物理参量。 关键词：Ni—Pb偏晶合金；快速凝固；液相分离；晶体生长；组织形态 中图分类号：TG146．1_5 文献标识码：A 文章编号：1001—4977(2009)08—0775—05 Phase Separation of Ni-Pb Monotectic Alloy During Rapid Solidification XU Jin-feng，FAN Yu—fang，CHEN Wei，ZHAI Qiu-ya (School of Materials Science and Engineering，Xi。an University of Technology Xi。an 71 0048，Shaanxi，China) Abstract：The rapid solidification of Ni—Pb monotectic alloy was investigated by melt—spun method， the alloy particles with a wide range of diameters frOm 40 to 400 lam and alloy ribbons with 4 mm in width and 30．50 um in thickness were produced respectively．Under rapid solidification，for N_．8％Pb hypomonotectic alloy．Ni phase grows in the form of dendrite and Pb-rich phase mainly distributes at grain boundary．With the rise of cooling rate。the microstructure was remarkably refined，the crystaI morphology of hypomonotectic alloy transforms frOm coarse dendrite to fine equiaxed dentrite．For N．．60％Pb hypermonotectic alloys．the rapid solidification can suppress the liquid phase separation to a great degree．which results in the formation of uniform microstructure of particles and ribbons．If both particle and ribbon ha