球磨时间对WC-6%Ni硬质合金微观结构及性能的影响

Effects of Ball-milling Time on Microstructure and Properties of WC-6%Ni Cemented Carbide

以WC-6%Ni硬质合金为研究对象,采用不同球磨时间制备了5组合金试样,通过对烧结后合金磁、力学性能的检测及显微结构观察,分析研究了球磨时间对WC-6%Ni硬质合金的微观结构及其性能的影响。结果表明:球磨时间对WC-6%Ni硬质合金的微观结构和性能影响明显,过短的球磨时间导致合金中存在粗大WC晶粒,适当延长球磨时间可使WC晶粒得到细化并获得微观结构均匀的合金,但过长的球磨时间则会导致合金中粗WC晶粒的再次出现。随着球磨时间的增加,抗弯强度、硬度、矫顽磁力均随之经历先上升到峰值后下降的过程;而球磨时间对WC-6%Ni合金的密度影响很小。当球磨时间为36 h时,WC-6%Ni硬质合金具有最小的WC平均晶粒度和相对均匀的微观结构,合金抗弯强度、硬度及矫顽磁力出现峰值,分别为2 250 MPa、89.4 HRA、4.9 kA/m。

Five groups of WC-6%Ni cemented carbide samples were prepared with different ball-milling time. After sintering, the properties and microstructure were tested and observed. The effects of ball-milling time on the microstructure and properties of the alloys were investigated. The results show that the ball-milling time is closely related to the microstructure and properties of WC-6%Ni cemented carbide. Short ball-milling time will lead to the presence of coarse WC grain. A proper ball-milling time enables the cemented carbide get appropriate WC grains and uniform microstructure. Coarse WC grains would appear again in the WC-6%Ni cemengted carbide when the ball-milling time is too long. With the ball-milling time increasing, TRS, hardness and coercive force decline after rising to a peak. It is found that the ball-milling time has almost no effect on the density of the alloy. The cemented carbide prepared with the powder via 36 hours ball- milling has the smallest average WC grain size and the most uniform microstructure, thus it has the highest TRS, hardness and coercive force in the five groups of samples, the values are 2 250 MPa, 89.4 HRA and 4.9 kA/m, respectively.