微量Y增强细晶W烧结行为和组织性能的研究

Study on Sintering Behavior, Microstructure and Property of trace yttrium enhanced fine -grained W alloy

摘要:

以“溶胶喷雾干燥-纳米原位复合”合成的超细/纳米W-0.3%Y复合粉末为原料,通过普通模压-预烧和在1800~1950℃下烧结制备细晶钨合金。检测了合金显微硬度和拉伸强度,并利用扫描电镜SEM和X射线能量色散谱(EDX)观察了断口形貌及显微组织,研究其烧结行为及断裂行为变化。结果表明：微量稀土Y以Y₂O₃二次相粒子的形式均匀弥散分布于W晶粒的晶内和晶界处,能有效抑制W晶粒的长大,显著细化晶粒,提高其力学性能。微量稀土Y的添加改变了W合金的断裂形式,由纯W的沿晶断裂转变为主要沿晶、部分穿晶的断裂方式。

Abstract:

Through the ordinary moulding - presintering, sintering at 1800-1950 ℃,the fine-grained tungsten alloys were fabricated with ultrafine/nano composite powders of W-0.3%Y which were prepared by Sol-spray drying- Nano in situ composite.The microhardness and tensile strength of alloys were detected,Moreover ,Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy were used to examine fracture morphology and microstructure .The evolution of Sintering and Fracture behavior were investigated.The results show that the added trace yttrium exists in the form of Y₂O₃ as the second phase particles dispersing throughout grain boundary and inner grain of W, restraining tungsten grain growth and making the grains to be significantly refined,which is to improve the mechanical properties of the alloys.Besides,The fracture mode of tungsten alloy with adding trace yttrium was changed from intergranular fracture transition of pure tungsten to mainly intergranular fracture and part transgranular fracture.