(西北工業(yè)大學(xué) 凝固技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，
西安 710072)
摘 要: 利用FGH95合金粉末在DD3單晶基材和定向凝固鎳基高溫合金的擇優(yōu)晶面（與擇優(yōu)晶向垂直的晶面）上進(jìn)行激光多層涂覆實(shí)驗(yàn)，得到了從基材外延生長的單晶涂覆層。 涂層由細(xì)小柱狀枝晶組織組成， 枝晶一次間距約為10μm， 二次臂退化。 由于局部凝固條件的不同， 枝晶干區(qū)域的γ′相為球形、 枝晶間區(qū)的γ′相為立方體形態(tài)， 尺度均小于0.1μm。 激光涂覆層中的主要元素Cr和Co的偏析比基材鑄態(tài)組織中的偏析大大減輕。 對標(biāo)準(zhǔn)熱處理后的試樣進(jìn)行分析表明: 試樣中的γ′相主要為方圓形， 且尺度均勻。 涂層中各元素的顯微偏析比熱處理之前有明顯減輕。沿片狀力學(xué)性能試樣柱狀晶生長方向進(jìn)行拉伸， 強(qiáng)度指標(biāo)達(dá)到同種材料粉末冶金試件的97.9%， 塑性超過粉末冶金試件。斷口分析表明， FGH95合金的斷裂機(jī)制為塑性斷裂。
關(guān)鍵字: 激光成形定向凝固； FGH95； 成分偏析； 力學(xué)性能
（State Key Laboratory of Solidification Processing, Northwestern Polytechnical University,Xi'an 710072, China）
Abstract:Laser multi-layer cladding experiments were performed on the preferential crystallography surface (plane normal to the preferential crystallography orientation) of the DD3 single crystal rod and the directional solidification nickel-base superalloy rod by using superalloy FGH95 powder. Cladding layers growing epitaxially from the substrate can be obtained. The cladding layer consists of thin columnar dendritic, the primary arm spacing of which is about 10μm, and the secondary arm is degenerated. γ′ deposits are spherical in the dendritic trunk and cubical in the interdendritic area due to the difference of the local elements aggregation. The sizes of γ′ phase are less than 0.1μm. Composition segregation of main elements in the cladding layer are highly alleviated on comparing with that of the substrate. After heat treatment, the γ′ deposits become cubic-spherical in the cladding layer and the size of them is more homogeneous in all of the single crystal cladding layers. Composition segregation is alleviated further after heat treatment. Mechanical measurement shows that yield strength acquires 97.9% of that in powder metallurgic sample and the plasticity surpasses that in powder metallurgic sample, and the fracture of FGH95 shows plastic fracture.
Key words: laser metal forming; directional solidification; FHG95; composition segregation; mechanical property
