Taking advantage of laser additive manufacturing, continuous SiC fiber reinforced titanium matrix composites (SiC/TMCs) with low density and excellent mechanical properties can be used to hybrid-fabricate large components with complex shape for aerospace applications. However, due to the anisotropy in both microstructure and heat transfer ability, the high-density and rapid heat input from laser during hybrid manufacturing process will cause the non-uniform damage of fibers and various solidification microstructure in the molten pool. In order to understand the solidification behavior of molten pool in SiC/Ti17 composites, the fixed-point laser surface remelting was used to bring in rapid and symmetrical heat input. With the decrease of temperature from center to edge of the molten pool, both fiber damage degree and the contents of Si and C elements in melt decreased. The solidification microstructure contains TiC, TiSi and β-Ti, and their morphology varies according to the melt composition. SiC fibers act as heterogeneous nucleation sites for first solidified phases and promote their preference growth along the radial direction of fibers resulting from the excellent heat transfer ability. The faceted TiSi grains solidified through peritectic reaction L+TiC→TiSi exhibit strong <0001> texture.

中文翻译：

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定点激光表面重熔诱导SiCf/Ti17凝固行为

利用激光增材制造技术，具有低密度和优异机械性能的连续碳化硅纤维增强钛基复合材料（SiC/TMC）可用于混合制造航空航天应用中形状复杂的大型部件。然而，由于微观结构和传热能力的各向异性，混合制造过程中激光高密度、快速的热输入会导致纤维的不均匀损伤和熔池中各种凝固微观结构。为了了解SiC/Ti17复合材料熔池的凝固行为，采用定点激光表面重熔引入快速、对称的热输入。随着熔池中心到边缘温度的降低，纤维损伤程度和熔体中Si、C元素含量均降低。凝固组织含有TiC、TiSi和β-Ti，它们的形貌根据熔体成分的不同而变化。 SiC纤维作为第一凝固相的异质成核位点，由于其优异的传热能力，促进其沿纤维径向择优生长。通过包晶反应 L+TiC→TiSi 固化的多面 TiSi 晶粒表现出强<0001>织构。