(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 采用选区激光熔化技术，结合旋转+填充扫描策略制备Rene104镍基高温合金，研究了成形参数对显微组织和开裂行为的影响。结果表明：线能量密度和扫描间距是影响Rene104镍基高温合金致密度及开裂的主要参数。当线能量密度为250 J/m，扫描间距为0.08mm时，Rene104镍基高温合金成形件的致密度达98.37%。选区激光熔化成形Rene104合金主要由横截面尺寸为0.5 μm、轴向尺寸为3~5 μm或30 μm的柱状晶组织组成，晶粒沿建造方向的(200)晶面择优取向生长，同时，在晶界存在碳化物和Laves相，出现了裂纹、孔洞及残留粉末颗粒等缺陷。高线能量密度产生的大温度梯度导致残余应力，从而在晶界析出相周围形成应力集中，在熔池和层间搭接处的熔池尖端萌生裂纹，且沿建造方向扩展。残留孔洞主要来自粉末空心缺陷，残留粉末颗粒则由粉末飞溅产生。
关键字: Rene104合金；选区激光熔化；致密度；显微组织；裂纹；碳化物
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The Rene104 nickel-based superalloy was fabricated by selective laser melting technology with the scan strategy of rotation plus filling, and the impacts of process parameters on the microstructure and cracking behavior were investigated. The results show the linear energy density and hatch spacing are the main parameters that affect the density and cracking behavior of Rene104 nickel-based superalloy. When the energy density is 250 J/m, and the hatch spacing is 0.08 mm, the relative density of Rene104 nickel-based superalloy samples reaches 98.37%. The Rene104 alloy is mainly composed of columnar grains with the cross-sectional dimension of 0.5 μm and the axial dimension of 3-5 μm or 30 μm. The grain grows along the build direction with the strong (200) texture, while the carbides and Laves phases exist along the grain boundaries. The defects, including cracks, pores and remained powders, are also be found. The high linear energy density can cause the large temperature gradient and residual stress, which results in the stress concentration around precipitates. Therefore, the cracks initiate at the pool tip and interlayer junctions, then extend along the build direction. The remained pores are mainly caused by the powder hollow, and the remained powders are generated by the powder splash phenomenon.
Key words: Rene104 superalloy; selective laser melting; relative density; microstructure; crack; carbide
