采用电子束物理气相沉积(EB-PVD)制备出大尺寸、超薄、化学成分均匀的TiAl/Ti3Al微叠层复合材料. 通过XRD和SEM对材料的相组成和微观结构进行了分析. 结果表明: TiAl/Ti3Al微叠层表面状态良好, 具有明显的层状结构, 相结构由α2-Ti3Al和γ-TiAl组成. 利用热等静压技术对微叠层进行了致密化处理, 经热等静压处理后的试样具有较高的拉伸强度, 并表现出较好的延伸率. 根据拉伸断口形貌及结构特征, 探讨了微叠层材料薄板的微观变形机制和断裂机理. TiAl/Ti3Al微叠层薄板经热等静压处理后, 材料断裂方式由沿晶脆性断裂转变为具有一定韧性的准解理断裂和沿晶脆性断裂的混合断裂方式.
In recent years, intermetallic compounds have received a lot of considerable attentions for high temperature applications in modern aircraft manufacturers, high temperature engine components, shape memory devices and power generation industry. Among these materials, Ti-Al intermetallic compounds are fascinating materials owing to their low density, high stiffness and good creep properties. However, the structure of the metallic bonding in these intermetallics is the important reason for their insufficient ductility at room temperature. In this work, large-sized TiAl/Ti3Al multi-layered composite thin sheet with uniform chemical composition was prepared by electron beam physical vapor deposition (EB-PVD) technology. The composite and microstructure of multi-layered composite were analyzed by XRD and SEM. The results indicated that the prepared material with visible lamellar structure was composed of α2-Ti3Al and γ-TiAl phases. The densification process of composite was carried out by hot isostatic pressing. The multi-layered material was evaluated with static tensile test before and after hot isostatic pressing. The multi-layered composite after hot isostatic pressing had a higher tensile strength and a good characteristic of tensile elongation. Based on the tensile fracture morphology, the microscopic deformation mechanisms and fracture mechanism were investigated. After hot isostatic pressing, the fracture mechanism transforms to a mixed mode which consists of intergranular fracture and cleavage fracture.
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