(中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083)
摘 要: 采用氧含量測定、XRD、SEM、能譜分析和顯微硬度測定，研究氧的添加方式對鐵基合金顯微組織和力學(xué)性能的影響。結(jié)果表明：在霧化加氧過程中，霧化液滴在冷凝時與氧接觸，使合金中引入氧原子，氧以固溶形式存在于霧化粉末中；粉末經(jīng)500 ℃氧化4 h后，氧達(dá)到擴(kuò)散固溶度后直接在粉末顆粒表面聚集，形成氧化膜；經(jīng)高能球磨后，氧在氧化粉末中的固溶度得到提高，氧以固溶的方式均勻分布在破碎的球磨粉末中；在退火態(tài)氧化粉末合金中，被拉長晶粒由未破碎粉末組成，內(nèi)部存在大量晶界，在晶界處氧含量偏高，析出相優(yōu)先形成，顯微硬度也較高；等軸晶由破碎的細(xì)小粉末顆粒組成，氧含量較低，合金的顯微硬度較低；霧化粉末經(jīng)球磨后氧分布較均勻，所獲得的鐵基合金硬度分布也較均勻。
關(guān)鍵字: 鐵基合金粉末；霧化；顯微硬度；第二相強(qiáng)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
