当前位置: X-MOL 学术Int. J. Refract. Met. Hard Mater. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Densification, microstructural evolutions of 90W-7Ni-3Fe tungsten heavy alloys during laser melting deposition process
International Journal of Refractory Metals & Hard Materials ( IF 3.6 ) Pub Date : 2020-04-08 , DOI: 10.1016/j.ijrmhm.2020.105254
Chun Li , Yingpei Wang , Shiyu Ma , Xiaoshan Yang , Jinfeng Li , Yuzhao Zhou , Xue Liu , Jingang Tang , Xiaoying Wang , Guomin Le

Thin walled 90W-7Ni-3Fe tungsten heavy alloys (WHAs) have been prepared by a laser melting deposition (LMD) additive manufacturing technique using different input laser volume energy densities. Detailed investigations on densification and microstructural evolutions of the LMD process have been carried out. The result shows that the sample density increases with increasing input energy density by elimination of “lack of fusion” defects. However, some gas delivered with powders gets trapped in the molten pool due to the fast cooling rate and complex shapes of W particles, resulting in a prevalence of small round pore defects even under high input energy densities. Near full density can be obtained when the energy density reaches 74 J/mm3. The LMD WHAs have two phase microstructures consisting of polygonal or dendritic W particles embedded in a nickel‑iron matrix, which has large sized columnar grains due to epitaxial growth. The polygonal particles are partially dissolved/melted W powder particles. The dendritic particles are newly formed grains due to the reprecipitation of supersaturated W in the nickel‑iron matrix during solidification. The proportion of dendritic particles increases with the increasing input energy density. A microstructure evolution process adapted from traditional liquid phase sintering process containing three stages of rearrangement, solution-reprecipitation, and solid state is proposed for the LMD process.



中文翻译:

90W-7Ni-3Fe钨重合金在激光熔融沉积过程中的致密化,微观组织演变

薄壁90W-7Ni-3Fe钨重合金(WHA)已通过使用不同的输入激光体积能量密度的激光熔融沉积(LMD)增材制造技术制备。已经对LMD工艺的致密化和微观结构演变进行了详细研究。结果表明,通过消除“融合不足”缺陷,样品密度随输入能量密度的增加而增加。但是,由于粉末的快速冷却速度和W颗粒的复杂形状,一些与粉末一起输送的气体被困在熔池中,即使在高输入能量密度下,也普遍存在小圆形孔缺陷。当能量密度达到74 J / mm 3时,可以获得接近全密度。LMD WHA具有两相微观结构,由嵌入铁镍基体中的多边形或树枝状W颗粒组成,由于外延生长,其具有大尺寸的柱状晶粒。多边形颗粒是部分溶解/熔融的W粉末颗粒。由于凝固过程中镍铁基体中过饱和钨的再沉淀,树枝状颗粒是新形成的晶粒。树突状颗粒的比例随着输入能量密度的增加而增加。针对LMD工艺,提出了一种基于传统液相烧结工艺的微观结构演变过程,该过程包括重排,固溶再沉淀和固态三个阶段。

更新日期:2020-04-08
down
wechat
bug