预烧结对低压烧结WC-Co硬质合金组织和性能的影响

采用原位还原碳化反应制备超细WC-10%Co,在1250、1300、1350、1380℃进行预烧结处理,得到的预烧结块体在1450℃、5 MPa氩气条件下进行低压二次烧结;分析对比了预烧结块体和二次烧结块体的显微组织,并对二次烧结合金进行了性能测试.结果表明:不同温度预烧结块体经低压二次烧结后,可有效抑制晶粒异常长大现象,二次烧结后合金具有高的断裂韧性,最高值达16.1MPa·m-1/2.在1 350、1 380℃下预烧结块体经低压二次烧结后均具有均匀的合金组织,其中经过1380℃预烧结块体横向断裂强度为3260 MPa.

Effect of Pre-sintering on Microstructure and Properties of Cemented Carbides Sintered by Sinter-HIP

In the present work,the in-situ synthesized ultrafine WC-Co composite powder was presintered at 1 250,1 300,1 350,and 1 380 ℃,respectively. Then,the pre-sintered solids were sintered by the hot isostatic pressing( sinter-HIP) at 1 450 ℃ for 30 min in the Ar atmosphere with gas pressure of5 MPa. Microstructures and mechanical properties of the pre-sintered solid and finally sintered bulks were investigated,respectively. Results show that the pre-sintering process can effectively control the abnormal grain growth. After pre-sintering treatment,the bulk materials prepared by sinter-HIP have excellent fracture toughness,with the maximum value of 16. 1 MPa·m- 1 /2. The composite powder pre-sintered at 1350 ℃ and 1 380 ℃,sintered by HIP,has more homogeneous microstructure and high transverse rupture strength.