摘要
研究了W-Ni-Fe纳米晶粉在注射成形中喂料的流变行为,纳米晶W-Ni-Fe粉采用机械合金化(MA)的方法制备,并将此粉末与蜡基粘结剂混合以形成一种喂料,讨论了MA球磨时间,纳米晶粉末体积和温度对喂料流变性的影响,随球磨时间增加,喂料的粘度以及粘度对剪切速率的敏感性降低,因此,在较长的球磨时间下,这种粉末喂料的流动性和成形性变好,随粉末体积增加,喂料的粘度遵循公式呈非线性增加,此时n=0.68.MA粉末喂料的粘度随温度和剪切速率的变化较小,所以注射温度和注射速度的变化对这种MIM注射坯的质量影响较小,本文也讨论了采用MA制备的W-Ni-Fe纳米粉末的烧结特性,实验结果表明球磨可以导致在液相烧结温度以下合金达到很高的密度,大的晶格畸变、晶粒细化和超饱和固溶体的形成,强化了烧结工艺。
The rheologic behavior of the nanocrystal W-Ni-Fe powder feedstock in MIM process was studied. The nanocrystal W-Ni-Fe powder was prepared by mechanical alloying (MA), and then was mixed with wax-based binder to form the feedstock. The effects of MA time, powder volumn and temperature on the rheologic behavior of the feedstock was discussed. The feedstock viscosity and its sensitivity to the shear rate decreased with increasing milling time. Therefore, the flowability and compactability of the feedstock was proved by a long milling time. With the volumn content of the powder increasing, the viscosity of the feedstock increased nonlinearly according to the following formula: η=ηο/A[1-(Φ/Φ_m)]~n (where n=0.68). The viscosity of the MA powder feedstock was influenced a little by the temperature and theshear rate, so the injection temperature and rate had little influence on this kind of green parts. The sintering characteristic of this MA-prepared W-Ni-Fe powder was also studied. Results showed that milling had led to a high alloy density when sintering below liquid phase temperature, and the sintering rate was accelerated by large crystal distortion, grain refining and supersaturated sosoloid.
出处
《粉末冶金材料科学与工程》
EI
1999年第3期169-174,共6页
Materials Science and Engineering of Powder Metallurgy
基金
国家"863"高技术计划资助项目
