微量Ti元素的添加对中颗粒WC-8%Co硬质合金微观结构及机械性能的影响

Effects of Trace Amount of Titanium Additions on Microstructures and Mechanical Properties of Medium-Grained WC-8%Co Cemented Carbides

以中颗粒原生WC粉、含有微量Ti元素的电解WC粉末及Co粉为原料,采用粉末冶金的方法分别制备原生WC-8%Co合金及电解WC-8%Co。在原生WC-8%Co中分别添加不同含量的Ti元素来探讨该元素对WC-8%Co合金微观结构与机械性能的影响,其中Ti元素以TiC的形式加入。测量合金的矫顽磁力、密度、硬度、抗弯强度及冲击韧性,使用金相显微镜、扫描电镜及X射线能谱仪对合金的微观结构进行分析。结果表明:电解WC-8%Co的抗弯强度与冲击韧性明显低于原生WC-8%Co合金。添加了微量TiC的所有WC-8%Co合金的硬度均大于原生WC-8%Co合金的硬度,且随着Ti含量的增加,合金的强度与冲击韧性呈现先降低后增加再降低的趋势。在电解WC-8%Co合金及添加TiC的合金中明显发现了第三相,随着TiC含量的增加,合金中的第三相由粗大状逐渐变成较小的近环状,第三相分布更均匀。

WC-8%Co cemented carbides are prepared from medium-grained virgin WC and electrolytic WC powders by conventional powder metallurgy technology.Different contents of titanium are added into virgin WC-8%Co,the effects of titanium additions on the microstructures and mechanical properties of WC-8%Co are investigated.The mechanical properties of the WC-8%Co are tested.The microstructure of WC-8%Co cemented carbide is observed by using scanning electron microscope.The result shows that the electrolytic WC-8%Co exhibits lower transverse rupture strength and impact toughness compared with that of the virgin WC-8%Co alloy.All virgin WC-8%Co alloy with different contents of titanium exhibit higher hardness values than that of the virgin WC-8%Co alloy without titanium.With the increasing of titanium addition,the transverse rupture strength and impact toughness of the composites decrease firstly,increase subsequently and decrease ultimately.The third phase is observed in electrolytic WC-8%Co and virgin WC-8%Co alloy with different contents of titanium.With the increasing of titanium addition,the morphology of the third phase is gradually changed from coarser shape to nearly circular shape with finer size and more uniform distribution.