(中南大學 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 以噴霧干燥−H2還原法制備的納米級90W-7Ni-3Fe復合粉末為原料，研究稀土La-Y含量對試樣燒結(jié)特性的影響，采用高倍SEM和金相儀器分別對斷口進行形貌觀察和W晶粒測試；對燒結(jié)樣的相對密度、抗拉強度、延伸率等性能進行測定與分析。結(jié)果表明：不添加稀土La-Y時，試樣在液相燒結(jié)時容易出現(xiàn)孔洞和氣泡，導致力學性能偏低；添加0.4%稀土La-Y(質(zhì)量分數(shù))時，合金的相對密度、抗拉強度和延伸率分別為99.4%、983.5MPa和15.2%； 添加0.4% La-Y后，在相界或晶界上形成了W13.61Ni2.61Fe1.07Y20.52La25.27On的中間相，阻止了W原子在粘結(jié)相中的擴散，阻礙了W晶粒長大，W晶粒由原來的20~25 μm減少到12~15 μm。
關(guān)鍵字: 90W-Ni-Fe合金；納米粉末；稀土La-Y；微觀結(jié)構(gòu)；力學性能
mechanical properties of nano-powder 90W-Ni-Fe alloy
（State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:Using nano-sized 90W-7Ni-3Fe composite powder synthesized by spray drying-H2 reduction method as raw material, the effects of La-Y content on sintering characteristic for specimens were studied. Fracture morphology and W crystal sizes were measured by SEM and optical metallography, respectively. And the relative density, tensile strength and elongation of sintering specimens were also measured and analyzed. The results show that the emergence of cavities and bubbles in sintering specimens leads to lower mechanical properties after liquid phase sintering when no La-Y is added. When 0.4% La-Y is added, the relative density, tensile strength and elongation of the alloy are 99.4%, 983.5MPa and 15.2%, respectively. When the La-Y content is 0.4%, the middle phase W13.61Ni2.61Fe1.07Y20.52La25.27On (molar ratio) forms at interface, which restrains the diffusion of W atom in matrix phase and prevents W crystal from growing up, and the average W crystal size decreases from 20−25 μm to 12−15 μm.
Key words: 90W-Ni-Fe alloy; nanosized powder; rare earth La-Y; microstructure; mechanical properties
