论文部分内容阅读
采用透明模型合金丁二腈-2.0%(质量分数)乙醇(SCN-2.0%Eth),实时观察了在单晶基材(001)晶面上进行激光重熔时,扫描方向偏离基材[100]晶向不同角度时熔池内枝晶生长的演化过程.研究发现,当沿平行[100]晶向的方向进行扫描时,熔池最后演变为[010]枝晶列和[01ˉ0]枝晶列平行对称生长;当扫描方向与[100]晶向的夹角为20°时,整个熔池呈现不对称振荡生长模式,即一侧一直呈[01ˉ0]枝晶列生长,另一侧呈[100]枝晶列和[010]枝晶列相互竞争交替生长;当扫描方向与[100]晶向的夹角达45°时,熔池一直呈现为[100]枝晶列和[01ˉ0]枝晶列相互垂直生长.根据枝晶择优生长准则,建立了一个描述熔池内枝晶生长行为的模型,很好地解释了实验结果.结果表明,熔池内凝固组织受熔池形态和基材晶体取向共同影响.
The laser melting of the (001) crystal plane of the single crystal substrate was observed in real time using the transparent model succinonitrile 2.0% (mass fraction) ethanol (SCN-2.0% Eth) ] Crystal at different angles, it is found that the molten pool finally evolves into dendritic column [010] and dendrite column [01-01] when scanned in a parallel [100] crystal orientation When the included angle between the scanning direction and the [100] orientation is 20 °, the entire pool exhibits an asymmetric oscillation growth mode, in which the dendrite grows in the order of [01 ˉ 0] dendrites and [100 ] Dendrites and [010] dendrites alternate with each other. When the included angle between the scanning direction and the [100] orientation reaches 45 °, the melt pool presents as [100] dendrite and [01-01] dendrites According to the principle of optimal growth of dendrites, a model describing the dendrite growth behavior in the molten pool was established, and the experimental results were well explained. The results show that the solidified structure in the molten pool is controlled by both the shape of the molten pool and the crystal orientation of the substrate influences.