(1. 北京科技大學 材料科學與工程學院，北京 100083；2. 海南大學 機電工程學院，海口 570228；
3. 廈門金鷺特種合金有限公司，廈門 361006)
摘 要: 采用普通市售中顆粒Ti(C,N)粉末，以一步燒結法制備脫β層梯度硬質合金；利用顯微組織分析和圖像分析等手段，研究合金初始成分對其微觀組織及脫β層厚度的影響規(guī)律。結果表明：當Ti(C,N)含量低于1.6%(質量分數)時，隨著Ti(C,N)含量的增加，脫β層厚度明顯增大，而當Ti(C,N)含量超過1.6%時，脫β層厚度呈緩慢縮小的趨勢；隨著鈷含量的增加，脫β層的厚度迅速增大，但當鈷含量達到10%(質量分數)左右時，在脫β層與芯部的界面處鈷相聚集現象嚴重；總碳含量為6.51%(質量分數)的合金中WC晶粒度較大且呈規(guī)則的多邊形，在1 450 ℃、2 h梯度燒結工藝下制備的脫β層厚度可達38 μm左右，而總碳含量為6.23%的合金中WC晶粒度較小且呈等軸化趨勢，同時脫β層的厚度僅為17 μm左右。
關鍵字: 梯度硬質合金；Ti(C,N)；初始成分；脫β層；微觀組織
（1. School of Materials Science and Engineering, University of Science and Technology Beijing,
Beijing 100083, China;
2. College of Mechanical and Electrical Engineering, Hainan University, Haikou 570228, China;
3. Xiamen Golden Egret Special Alloy Co., Ltd., Xiamen 361006, China）
Abstract:The graded cemented carbides with cubic carbide free layer (CCFL) were fabricated by one-step sintering procedure using Ti(C,N) powder with medium particle size as the raw material, and the effect of starting composition on the microstructure and thickness of CCFL was discussed in detail by scanning electron microscopy and soft Image Tool. The results show that, the thickness of CCFL increases gradually with the increase of Ti(C,N) content when it is lower than 1.6% (mass fraction), whereas the thickness of CCFL decreases slightly with the increase of Ti(C,N) content when it exceeds 1.6%. The thickness of CCFL increases rapidly with the increase of Co content, whereas the Co phases are inclined to aggregate in the border between CCFL and core zone when the cobalt content reaches 10% (mass fraction). The WC particles in alloy with total carbon content of 6.51% (mass fraction) are larger in size and show regular polygon usually, the depth of CCFL can reach about 38 μm under the graded sintering process of 1 450 ℃ and 2 h; while in the alloy with total carbon content 6.23% , the WC particles are smaller in size and tend to be spheroidal shape, and the depth of CCFL is only about 17 μm under the same sintering procedure.
Key words: graded cemented carbide; Ti(C,N); starting composition; cubic carbide free layer (CCFL); microstructure
