热分解碳对注射成形钼合金性能和显微组织的影响

Effect of thermal decomposed carbon on properties and microstructures of molybdenum alloys prepared by powder injection molding

采用粉末注射成形方法制备Mo-Ti-Zr合金,研究热分解碳对钼合金性能和组织的影响。研究结果表明,碳含量少时,合金密度提高,并且碳可形成细小弥散的第二相粒子,使得合金性能得到强化;碳含量较高时,容易与钼基体及添加元素反应形成脆性的第二相颗粒,这些第二相颗粒在拉应力作用下发生断裂,加上注射试样本身存在较多的孔洞,容易成为裂纹源,使得合金的性能降低。热分解碳能有效阻止杂质元素氧与钼基体及添加的微量元素反应,降低晶界处的氧含量,起到净化晶界的作用。

Mo-Ti-Zr alloys were prepared by powder injection molding.The effects of thermal decomposed carbon on the properties and microstructures of the obtained alloys were studied.The results show that the higher alloy density and smaller dispersed second phase particles can be obtained when the carbon content is low,and the dislocation can only pass the second phase particles when the stress is higher,which result in the improving properties of the alloy.The high content of thermal decomposed carbon can cause the formation of brittle secondary phase particles,by reacting with Mo substrate,which can crack easily under applied tensile stress.In addition,many pores existing in the injection compacts are prone to inducing micro-cracks,leading to decrease the mechanical properties of the sintered alloys.The thermal decomposed carbon can effectively prevent oxygen from reacting with the substrate as well as the alloying elements of Ti and Zr,which reduces the oxygen concentrations aggregating along the grain boundaries.