W-Ni-Fe纳米晶粉末的流变特性(英文)

Rheological Behavior of W-Ni-Fe Nanostructured Powder

研究了Ｗ－Ｎｉ－Ｆｅ纳米晶粉末的注射成形（ＭＩＭ）。纳米晶粉末采用机械合金化（ＭＡ）的方法制备，然后将这种纳米晶粉末与蜡基粘结剂混合以制备出喂料。讨论了ＭＡ球磨时间、纳米粉末的体积装载量和实验温度对喂料流变行为的影响。结果表明，随球磨时间增加，喂料粘度降低，粘度对剪切速率的敏感性也降低。因此，随球磨时间增加，喂料的流动性和成形性变好。随粉末装载量增加，喂料粘度呈非线性增加。喂料粘度与粉末装载量的关系为： ，其中ｎ＝０．６８。粉末经球磨后，粘度变化随温度和剪切速率的变化不大。因此，注射温度和注射速度的变化对ＭＩＭ产品的质量影响不大。

The nanocrystalline powder of W-Ni-Fe alloy used for Metal Injection Molding(MIM) has been studied. The nanopowder prepared by Mechanical Alloying (MA) was mixed with a wax-based binder to form a feedstock. The effects of MA milling time, nanopowder volume fraction and temperature on the theological behavior of the feedstock are discussed. With increase of 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 at the condition of long time milling become better. With increase of powder volume fraction, the viscosity of the feedstock has a non-linear increase, which follows the formula: eta=eta (0)A[1 - (phi/phi (m))](-n) Here n is equal to 0.68. The change of viscosity with temperature and shear strain late is small for the MA powder, so the quality of these MIM products is not strongly effected by the changes of temperature and injection speed.