摘要:
针对电子束选区熔化纯钨晶粒粗大的问题,选取B作为晶粒细化元素,探索了成形工艺参数对W-B合金的致密化、显微组织和力学性能的影响。研究发现:在成形工艺参数为I=15 mA,v=300 mm·s-1,E=1200 J·mm-3时,W-B合金试样致密度最高,孔洞及未熔合缺陷最少,微裂纹基本得到抑制。引入B元素造成的成分过冷有效细化了电子束选区熔化成形W的晶粒尺寸,显微组织由粗大柱状晶转变为细小的柱状树枝晶,平均晶粒尺寸为8.26 μm。W-B合金的最高硬度达到672 HV,最高抗压强度达到1598 MPa,断裂机制为解理断裂。
Abstract:
In view of the coarseness of grains in microstructure of pure tungsten after selective electron beam melting (SEBM), B was selected as the grain refinement element. Besides, the influence of forming process parameters on the densification, microstructure and mechanical properties of W-B alloy was explored. It is found that when the forming process parameters are I=15 mA, v=300 mm·s-1 and E=1200 J·mm-3, the density of W-B alloy samples is the highest, and the pores and unfused powders are the least, the microcracks were basically suppressed. The constitutional undercooling caused by the introduction of element B effectively refined the grain size of W formed by SEBM, and the microstructure changed from coarse columnar crystal to fine columnar dendrites with an average size of about 8.26 μm. The highest hardness of W-B alloy is 672 HV, and the highest ultimate compressive strength is 1598 MPa. The fracture mechanism is mainly cleavage fracture.
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