铈、镧、钇、铼、钾对钨材料的强化机制探讨

Discussion on Strengthening Mechanism of Lanthanum, Cerium, Yttrium, Rhenium,Potassium on Tungsten Materials

分别将铈、镧、钇、铼、钾添加入钨粉中,经过等静压和2 300℃烧结,然后通过打断、拉拔或轧制等手段制成相应的样品,采用扫描电镜观察、能谱分析等实验手段,检测试样的微观组织结构,结合裂纹、固溶、应力进行分析,探讨了铈、镧、钇、铼、钾对钨材料的强化机制。结果表明,含铈、镧、钇的钨材料的细晶强化和颗粒强化是通过阻碍钨晶界微裂纹扩展实现的;铼含量较低时,钨铼合金的固溶对材料固溶强化作用不明显,而是修复钨晶界微裂纹;钾泡强化能起作用的原因是钾元素微量固溶于钨晶粒,使钾原子进入钨晶粒内部,降低了钾泡内部的蒸汽压力,同时修复钨晶界的微裂纹,压力加工时受挤压的钾泡在固溶的作用下朝球形转化,降低了材料内部应力集中。

Cerium, lanthanum, yttrium, potassium and rhenium were added into tungsten powder, respectively. After static pressing and sintering at 2 300 ℃, samples were prepared by means of interrupt, drawing or rolling of the sintered tungsten samples. Using scanning electron microscope, energy spectrum analysis and other experimental methods, microstructures of tungsten materials with adding elements were detected. Combined with the crack, solid solution and stress analysis, the strengthening mechanism of lanthanum, cerium, yttrium, rhenium, potassium on tungsten materials were discussed. Results show that fine grain strengthening and particulate reinforcement on Ce,La,Y containing tungsten materials are realized by hindering of micro crack extension in tungsten grain boundary. When the Re content is low, the strengthening effect in tungsten rhenium alloy is not solid solution, but the repairment of tungsten grain boundary micro crack. The reason for potassium bubble strengthening is solid solution of trace potassium in the tungsten grain. Potassium atom penetrates into the tungsten grain interior, which reduces potassium bubble internal steam pressure, meanwhile repairs tungsten grain boundary micro crack. During pressure processing, the extruded potassium bubble transforms toward spherical under the effect of solid solution, which reduces the internal stress concentration of the material.