(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 利用弯曲性能测量、金相、SEM观察和EDS分析等方法，对不同C含量的Mo-C棒横向弯曲性能及组织进行研究。结果表明：1号Mo-C棒中C含量(摩尔分数)为290×10−6，O含量为25×10−6，2号Mo-C棒中C含量为150×10−6，O含量为25×10−6；在同样条件下，2号Mo-C棒的横向弯曲性能更好；2号Mo-C棒的再结晶温度为950~1 100 ℃左右；随着退火温度的升高，合金的横向弯曲性能逐渐提高，在1 100 ℃时，合金的横向弯曲伸长率最高，达到10%；纯钼的断裂方式以沿晶断裂为主，添加C后，合金的裂纹扩展应力得到提高，合金的断裂方式变成以穿晶断裂为主，断口上有大量的解理面，具有明显的河流状花样和解理台阶；当添加的C含量偏高时，合金中生成大颗粒的碳化物，这种大颗粒的碳化物降低了合金的塑性。
关键字: Mo-C棒；横向塑性；沿晶断裂；穿晶断裂
molybdenum-carbon bars
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract: The transversal bending property and microstructure of molybdenum-carbon bars under different conditions were investigated by bending property measurement, optical microscopy, scanning electron microscopy and EDS. The results show that the molar fractions of C and O in Mo-C bar No.1 are 290×10−6 and 25×10−6, respectively, and those in Mo-C bar No.2 are 150×10−6 and 25×10−6, respectively. The transversal bending property of Mo-C bar No.2 is better than that of Mo-C bar No.1 under the same condition. The recrystallization temperature of Mo-C bar No.2 is 950−1 100 ℃ and during the annealing process, the transversal bending property is gradually improved and the elongation of the transversal bending reaches a maximal value of 10% at 1 100 ℃. The fracture type of pure Mo is intergranular fracture, the enhancement of the crack propagation stress of the Mo-C alloy is due to the addition of carbon, which makes the fracture type change to a transgranular fracture type. A large number of cleavage planes and steps are observed on the bending fracture surface. But if the carbon content is too high, the carbide precipitation will be severe at grain boundaries and decrease to the ductility of the alloy.
Key words: Mo-C bars; transversal plasticity; intergranular fracture; transgranular fracture
