纳米钨合金粉末常压烧结的致密化和晶粒长大

来源期刊：中南大学学报(自然科学版)2001年第4期

论文作者：范景莲 黄伯云 张传福 曲选辉

文章页码：390 - 393

关键词：钨合金;致密化;纳米粉末;晶粒长大

Key words：tungsten heavy alloy; densification; nano-powder; grain growth

摘    要：高密度合金由于具有密度和强度高、延性好等一系列优异的性能,在军工上被用作动能穿甲弹材料.纳米材料被认为是21世纪应用前景非常广阔的新型材料,采用纳米粉末可望大大细化钨合金晶粒,显著提高合金的强度、延性和硬度等力学性能,因而是制备新型高强韧高密度钨合金的很重要的研究方向.作者采用机械合金化(MA)工艺制备了纳米钨合金复合粉末,研究了纳米钨合金粉末在常压氢气气氛中的烧结致密化和在烧结过程中的W晶粒长大行为.同时,指出了在液相烧结时存在的问题,即W晶粒加速重排、产生晶粒聚集与合并,迅速发生W晶粒长大,在较短时间内液相烧结时,W晶粒尺寸又长大到接近传统高密度合金水平.研究结果表明,MA纳米粉末促进了致密化,使致密化温度降低100~200℃;在一般固相烧结温度时可以得到晶粒粒径为3~5μm的细晶高强度合金.

Abstract: Tungsten heavy alloy is regarded as a very important kinetic penetrator in military use, due to its combined physical and mechanical properties, such as high density, high strength and hardness, good ductility. Nano-material is a newmaterial with wide application in the 21th century. Using nano-powder as initial powder, the tungsten grain size can be greatly decreased, while the tensile strength, ductility and hardness can be greatly increased. Thus, it is an important orientation of preparation of a new tungsten heavy alloy with super high strength and ductility. In this paper, the nano-powderwas prepared by using MA, the sintering densification and grain growth behavior under constant pressure during sintering in hydrogen atmosphere were studied. The results show that, using nano-powder, the densification is greatly enhanced. The densification temperature can decrease by 100~200℃. After solid state sintering at 1 400℃,the densified alloy with very fine grain size is obtained. At the same time, the key problems of the nano-powder during liquid phase sintering were pointed out in this paper, that is, double speed oftungstengrain re-arrangement and grain coalescence result in rapid grain growth. After holding for a short time during liquid phase sintering, the tungsten grain size is increased near that of traditional liquid phase sintering.