The rheological and sintering behavior of W–Ni–Fe nano-structured crystalline powder
The rheological and sintering behavior of W–Ni–Fe nano-structured crystalline powder
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DOI：
10.1016/s0924-0136(02)01090-7
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发表时间：
2003-06
影响因子：
6.3
通讯作者：
Bai-yun Huang;Jinglian Fan;S. Liang;X. Qu
中科院分区：
文献类型：
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作者：
Bai-yun Huang;Jinglian Fan;S. Liang;X. Qu
研究了注射成形用纳米晶W-Ni-Fe合金粉末。这种通过机械合金化（MA）制备的纳米粉末与蜡基粘合剂混合以形成原料。讨论了MA球磨时间、纳米粉体积分数和温度对喂料流变行为的影响。随着球磨时间的增加，喂料粘度降低，粘度对剪切应变速率的敏感性降低。因此，该粉末原料在较长时间研磨的条件下的流动性和成型性变得更好。随着粉末体积分数的增加，喂料的粘度呈非线性增加，符合公式η=η0A[1-（Φ/Φm）]-n。这里n等于0.68。MA粉末的粘度随温度和剪切应变速率的变化较小，因此温度和注射速度的变化对MIM制品的质量影响不大。实验表明，在液相烧结温度以下，球磨可获得高密度的W-Ni-Fe粉末。并对该纳米粉体的机械合金化烧结特性进行了讨论。由于MA粉末的晶格畸变、晶粒细化和过饱和固溶体促进了固结过程，可获得较高密度和强度的W-Ni-Fe纳米粉末制品。
Nano-crystalline powder of W–Ni–Fe alloy used for metal injection molding (MIM) was studied. This nano-powder, prepared by mechanical alloying (MA), was mixed with a wax-based binder to form a feedstock. The effects of MA milling time, nano-powder volume fraction and temperature on the rheological behavior of the feedstock are discussed. With increase of the milling time, the viscosity of the feedstock and the sensitivity of viscosity to shear strain rate decrease. Therefore the fluidity and formalization of this powder feedstock under conditions of longer time milling become better. With increase of the powder volume fraction, the viscosity of the feedstock has a non-linear increase which follows the equation η=η0A[1−(Φ/Φm)]−n. Here n is equal to 0.68. The change of viscosity with temperature and shear strain rate is small for the MA powder, so the quality of these MIM products is not affected strongly by the changes of temperature and injection speed. The experiments show that the milling of W–Ni–Fe powder leads to high density below the liquid sintering temperature. The sintering characteristics of this nano-powder by MA are also discussed. Because the lattice distortion, grain refining and supersaturated solid solution of MA powder promote the consolidation process, higher density and strength of W–Ni–Fe nano-powder products can be obtained.