WC原料的多晶结构对合金组织及性能的影响

Effect of polycrystalline structure of WC raw materials on microstructure and properties of alloys

由于检测方法的限制,对WC粉体结构的研究和WC粉体结构对合金性能影响的研究在过去一段时间内多以"颗粒"作为其基本单元进行分析。本文采用EBSD技术,利用WC晶粒之间的取向差从多晶颗粒中分辨出WC单晶,实现了对多晶颗粒内部结构的检测,进一步研究了多晶结构对合金组织结构与性能的影响。研究结果表明,WC粉体中存在的大量多晶结构体,其在球磨过程中一部分会被破碎成粒径细小的单晶体,同时依然会有部分保留在混合料中。这些破碎后的细小颗粒会在后续的烧结过程中引起WC晶粒的异常长大,而在球磨态中残留的未破碎的多晶颗粒在后续的烧结中,则会引起WC团聚,增加了合金中WC/WC界面,引起合金断裂韧性K_(ⅠC)的下降。

Due to the limitations of the detection methods, the study of the WC powder structure and the effect of the WC powder structure on the properties of the alloy have been analyzed with ＂particles＂ as their basic unit in the past period of time. In this paper, by using the EBSD technique, the WC single crystal particles are distinguished from the polycrystalline particles by the difference in orientation between the WC grains, and the internal structure of the polycrystalline particles is detected. Based on this, the polycrystalline structure is further studied. Further more, the influence of polycrystalline structure on the microstructure and properties of the alloy is studied. The results show that a large number of polycrystalline structures present in the WC powder are partially broken into fine-grained single crystal particles in the ball milling process, and some of them remain in the mixture. These broken fine particles will cause abnormal growth of WC grains in the subsequent sintering process, while the unbroken polycrystalline particles remaining in the ball-milled state will cause WC agglomeration in the subsequent sintering process, which increasing the WC/WC interface in the alloy, causing the decrease of the K_（ⅠC） of the alloy.