(中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室， 長(zhǎng)沙 410083)
摘 要: 以噴霧干燥-H2還原法制備的納米級(jí)90W-7Ni-3Fe復(fù)合粉末為原料, 研究了不同稀土Y含量對(duì)試樣燒結(jié)特性的影響, 采用掃描電鏡和金相儀器分別對(duì)斷口進(jìn)行了形貌觀察和W晶粒粒度測(cè)試； 并對(duì)燒結(jié)樣的相對(duì)密度、 抗拉強(qiáng)度、 延伸率等性能進(jìn)行了測(cè)定與分析。 研究結(jié)果表明： 不添加稀土Y時(shí)， 試樣在液相燒結(jié)時(shí)容易出現(xiàn)孔洞和氣泡, 導(dǎo)致試樣力學(xué)性能偏低； 當(dāng)添加稀土Y后, 燒結(jié)樣中沒有孔洞和氣泡, 添加0.4％~0.6%稀土Y（質(zhì)量百分?jǐn)?shù)）時(shí), 合金相對(duì)密度、 抗拉強(qiáng)度和延伸率分別為99.6%、 1 080 MPa和17.6%； 添加0.4%Y后, W晶粒從原來的20~25 μm減小到10~12 μm, W晶粒由不加稀土?xí)r的球形變?yōu)榻蛐位蚨噙呅? 且隨稀土含量的增加其影響作用更明顯； 在相界或晶界上形成了W13.07Ni2.96Fe1.52Y23.65Ox(摩爾比)的中間相, 阻止了W原子在粘結(jié)相中的擴(kuò)散及W晶粒的長(zhǎng)大。 建立了合金中W顆粒的三層微觀結(jié)構(gòu)模型。
關(guān)鍵字: 90W-7Ni-3Fe合金； 納米級(jí)粉末； 稀土Y； 燒結(jié)特性
（ State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: Nanosized 90W-7Ni-3Fe composite powder synthesized by spray drying-H2 reduction method was used as raw material. Effects of sintering characteristics for specimens were studied by adding different contents of Y. Fracture morphology and W crystal sizes were measured by scanning electron microscopy and optical microscopy, respectively. Relative density, tensile strength and elongation of sintering specimens were also measured and analyzed. The results show that the emergence of cavities and vapour inner sintering specimens leads to low mechanical properties during liquid phase sintering with no addition of Y. Cavities and vapour in sintering specimens disappear when adding some Y. When the Y addition is 0.4%-0.6%, the relative density, tensile strength and elongation of alloy are 99.6%, 1 080 MPa, 17.6%, respectively. Average W crystal size decreases from 20-25 μm to 10-12 μm by adding 0.4% Y, and the W crystal morphology is nearly spherical or polyhedron. The higher the rare earth addition is, the bigger influence on W crystal morphology is. Middle phase W13.07Ni2.96Fe1.52Y23.65Ox (mole ratio) appears at interface when rare earth Y is added, which decreases the diffuse of W atom in matrix phase and prevents W crystal from growing up. The three layer microstructure model image of W particle inner alloy was established.
Key words: 90W-7Ni-3Fe alloy； nanometer powder； rare earth Y； sintering properties
