粉末粒度对钨钼双金属性能影响

Properties of W/Mo Bimetal with Different Powder Particle Sizes

使用不同粒度钨粉，包括2．0～3．0μm（粗粉）、1．0～2．0μm（细粉）、特定比例粗细混合粉，同粒度为4．0～5．0μm钼粉制备钨钼双金属坯料，氢气气氛下，在2150℃高温保温5h烧结，对样品进行界面组织、成分和力学性能等分析，结果表明：在实验条件下，3组样品均得到具有一定结合强度的双金属材料，其中粗钨粉烧结所得样品烧结不充分，孔隙率大，密度较低，剪切强度为171．97MPa；细钨粉烧结所得样品密度最大，但界面有微裂纹，应为双金属层烧结及冷却收缩产生较大的收缩差异导致，剪切强度为234．8MPa；粗细混合钨粉制备双金属样品密度及空隙率居中，界面微观组织结合良好，有明显的互扩散过渡层，厚度在0．1～0．2mm，剪切强度为224．71MPa，综合性能最优。W粉粒度组成直接影响双金属样品结合性能，通过调整粉末搭配，可改善因密度、气孔、烧结收缩等引起的缺陷，从而提高双金属烧结制品性能。

W/Mo bimetallic samples were prepared with 4.0 - 5.0 μm Mo powder and three different particle sizes of W powders including 2.0 - 3.0μm（ coarse particle）, 1.0 - 2.0 μm （ fines particle） , and mixed powder by specific weight proportion, under the condition of 2150 ℃preservation 5 h and hydrogen sintering. By analyzing the interface structure, composition and mechanical property, the results showed that each of the three samples had a certain bonding strength under laboratory conditions. The coarse particle sample was not sintered sufficiently. It had a high porosity and a low density. The shear strength was 171.97 Mpa. The fine W particle sample had the biggest density. But the interface had microcracks, which might result from the shrinkage difference in heating and cooling process. And the shear strength was 234.8 Mpa. The mixed powder sample had the best combination property. The density and void ratio had a middle level in the three sample. It had a good interface microstructure, and had an obvious mutual diffusion transition layer about 0.1 -0.2 mm thickness. The shear strength was 224.71 Mpa. The properties of W/Mo bimetal was influenced directly by W powder particle size. The defects from factors of density, porosity, and sintering shrinkage could be improved through adjusting the powder form, and the properties of bimetal sintered products would be guaranteed.