(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 采用氧含量测定、XRD、SEM、能谱分析和显微硬度测定，研究氧的添加方式对铁基合金显微组织和力学性能的影响。结果表明：在雾化加氧过程中，雾化液滴在冷凝时与氧接触，使合金中引入氧原子，氧以固溶形式存在于雾化粉末中；粉末经500 ℃氧化4 h后，氧达到扩散固溶度后直接在粉末颗粒表面聚集，形成氧化膜；经高能球磨后，氧在氧化粉末中的固溶度得到提高，氧以固溶的方式均匀分布在破碎的球磨粉末中；在退火态氧化粉末合金中，被拉长晶粒由未破碎粉末组成，内部存在大量晶界，在晶界处氧含量偏高，析出相优先形成，显微硬度也较高；等轴晶由破碎的细小粉末颗粒组成，氧含量较低，合金的显微硬度较低；雾化粉末经球磨后氧分布较均匀，所获得的铁基合金硬度分布也较均匀。
关键字: 铁基合金粉末；雾化；显微硬度；第二相强化
iron-based alloy 14YWT
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The effects of the oxygen addition manner on microstructures and mechanical properties of Fe-based alloy were investigated by oxygen analysis, X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy spectrum analysis and microhardness test. The results show that the oxygen atom is incorporated into the alloy when the atomized droplet contacts with oxygen during the condensation process. The existing manner of oxygen in the atomized powders is solid solution. The oxygen dissolves uniformly in the oxidized powder and a very thin layer of oxides forms on the powder surface after sintering at 500 ℃ for 4 h. The solid solubility of oxygen in the iron-based powder increases after the mechanical alloying (MA). The oxygen as solid solute distributes evenly in the fractured atomized powders. The oxygen content increases at the grain boundary of the elongated grains composed by the unfractured MA powder. The precipitated phase preferentially forms at the grain boundary which strengthens the iron-based alloy with oxidized powder, therefore the microhardness increases. The oxygen content in the equaixed grain composed of fine particles is very low, and the microhardness of the alloy decreases. The oxygen of the MA atomized powder distributes evenly, and the microhardness of the iron-based alloy also distributes evenly.
Key words: iron-based powder; atomization; microhardness; precipitated-phase strengthening
