孔隙率对Ti-Al金属间化合物多孔材料拉伸性能的影响

Effects of Porosity on Tensile Properties of the Ti-Al Intermetallic Compound Porous Material

摘要:

采用元素混合粉偏扩散-反应合成-粉末烧结方法制备了Ti-Al金属间化合物多孔材料，对其进行了拉伸试验研究，分析其拉伸变形特征，揭示出孔隙率对拉伸性能的影响规律以及拉伸断裂微观机理。结果表明：Ti-Al多孔材料的拉伸应力-应变曲线大致可分为弹性、屈服、强化和破坏4个阶段，无颈缩现象；力学性能指标（如弹性模量、屈服极限和强度极限等）均随孔隙率的增大而减小，延伸率远低于5%，呈现出明显的室温脆性；断口特征宏观上表现为脆性断裂，微观上同时存在穿晶断裂与沿晶断裂，其断裂机理与Ti-Al金属间化合物致密体的显微组织密切相关

Abstract:

Ti-Al intermetallic compound porous material was prepared by the element mixture partial diffusion-reactive synthesis-sintering method. Its tensile deformation was studied experimentally. The effect of porosity on the tensile properties and its microscopic fracture mechanism in tension were revealed. Results show that the tensile stress-strain curve can be divided into four stages: elasticity, yielding, strengthening and failure without necking. Its mechanical properties (including elastic modulus, yield strength and ultimate strength) decrease with the increasing of the porosity and the elongation is much lower than 5%, indicating obvious brittleness at room temperature. The characteristic of the fracture surface is of brittle fracture in macroscopy and of transgranular and intergranular fracture existing simultaneously in microscopy, which is closely related to the microstructure of the dense Ti-Al intermetallic compound.