Study On The Preparation And Interface Properties Of Ti/Al₃Ti Laminated Composites

The recent studies with respect to Ti/A13Ti laminated composite, which is a new class of laminated composite with low density, high strength, high modulus and excellent good toughness characteristics, are mostly focused on the preparation technology, fracture mechanism and so on. As we all know that interface plays an important role in the physical and mechanical properties of the composites. While,there are few studies on interface of this novel laminated composite. Therefore, in order to investigate the interface properties of Ti/A13Ti laminated composite, firstly,vacuum hot press sintering method is used to prepare this composite, and the properties of laminated composite including compressive properties under different strain rates and interlamination fracture (?+? and ? type) are carried out by means of INSTRON universal load frame and Hopkinson bar.The experimental results show that, the Ti/A13Ti laminated composite consisting of only Ti and A13Ti phase, derived from original Ti foils and Al foils using the vacuum hot sintering method, has few defects, while the interface between Ti and A13Ti layer of the composite combined well according to the result of microstructure observation. The compressive strengths of Ti/A13Ti laminated composite under quasi-static loading condition are 1250MPa and 1100MPa,respectively, when the loading is perpendicular and parallel to the layers. Meanwhile,when the loading is perpendicular to the layers, the dynamic compressive strength is 1350MPa under high strain rate. Obviously, by comparing the compressive properties under different strain rates, it can be concluded that the Ti/A13Ti laminated composite is sensitive to strain rate, i.e. the compressive strength increases with increasing strain rate. The energy release rate of ? type laminated fracture is significantly higher than that of ?+? hybrid type. And the energy release rate of ? type interlaminate fracture increases with increasing loading rates, while that of ?+? hybrid type interlaminate fracture decreases. In addition, some influence factors such as layer number and pre-crack size of sample affect the energy release rate of interlaminate fracture investigated in this thesis. The results of energy release rates of ? type and ?+? hybrid type interlaminate fracture show that there exists a critical number for Ti layers, and with the increasing pre-crack size of sample, the energy release rate of ?+? type interlaminate fracture increases. The fracture morphology shows that the crack deflection is of overwhelming importance owing to the weak interface of the laminated composite, which improves the fracture toughness of laminate composite.