显微组织的影响
(中南大学 粉末冶金国家重点实验室,长沙 410083)
摘 要: 采用喷雾干燥−热还原的方法制备纳米级93W-4.9Ni-2.1Fe复合粉末和微量稀土掺杂的复合粉末,研究微量稀土掺杂对烧结致密化和晶粒尺寸的影响。结果表明:微量稀土掺杂能有效地降低该复合粉末的晶粒尺寸,并能改善粉末的分散度;纳米级复合粉末在1 380~1 410 ℃液相烧结可实现材料的近全致密化,比同种成分的传统钨合金的烧结温度降低了120 ℃左右,合金的相对密度可达99%以上;但微量稀土掺杂对烧结的致密化有一定的抑制作用;同时微量稀土元素对合金的晶粒尺寸的抑制作用主要发生在液相烧结阶段。
关键字: 钨合金;W-Ni-Fe复合粉末;Y2O3掺杂;烧结行为;显微组织
fine-grain W-Ni-Fe powders
(State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: Nano-grained W-Ni-Fe composite powders and Y2O3 doped W-Ni-Fe composite powders were fabricated by spray drying and subsequent thermal reduction process. The influence of trace Y2O3 on the sintering behavior of Y2O3 doped W-Ni-Fe composite powders was investigated. The results show that trace rare earth addition can reduce the crystalline size proficiently; The near full densification can be realized in the temperature range from 1 380 ℃ to 1 410 ℃, which is 120 ℃ lower than the temperature of sintered traditional tungsten heavy alloys. The relative density can achieve 99%, and trace rare earth element restrains the growth of tungsten grain, which happens mainly at the liquid phase sintering.
Key words: tungsten heavy alloy; W-Ni-Fe composite powder; Y2O3 doped; sintering behavior; microstructure