Study On Deformation Of Ti-Al Layered Composite Based On DIC Techniche

Local strain distribution has a great impact on the plastic deformation of Ti-Al layered composite. In this paper, micron level Ti-Al layered composite was prepared with the way of hot-rolling. By scanning electron microscopy, transmission electron microscopy, etc, Ti-Al layered composite was used to structure analysis and mechanical performance test, and study on the effect of layered structure parameters on the Ti-Al layered composite. Using DIC technology, it researchs plastic deformation properties of Ti-Al layer composite from the perspective of local strain distribution: under macroscopic scales, different macro variables should be related to local strain distribution; On the microscopic scales, local strain in specific area(interface) has the influence law with the plastic deformation increasing by the quantitative characterization. Through the local strain distribution measurement, the goal reveals the layered compositel toughness essential reason.Ti-Al layered composite which is same thickness ratio and different thickness was fabricated by hot press and rolling, and the thickness is 480-480μm, 240-240μm, 100-100μm, 60-60μm four system. SEM microstructure analyses show Ti-Al layered composites which have a thickness of 100-100, have the most uniform thickness of each component, and the interface is flat, seamless, with good interface. By EBSD analysis, Ti-Al layered composite exhibited mainlybasal texture. layer texture is mainly < 0002 > //ND base texture. By TEM analysis, it was observed the interface layer Ti Al3, size at 100 nm.Through the room temperature tensile test, test Ti-Al layr\erd composite board room temperature tensile properties, the results show th at with the increase of thickness, Ti-Al layered composite tensile strength and elongation have been increased, elongation as the layer thickness increases from 33% to 38%;Tensile strength from 246 mpa to 246 mpa, strength increased by about 35%From the in situ tensile which based on DIC in macro scale, local strain distribution of single-layer Ti and Ti-Al layer composites and their regularities along with the macro variable were got. As for the Plastic deformation evolution of local strain distribution rule, the length of the local strain distribution is a important indicator for measure the plastic of the material. Lateral local strain distribution gradient lead to the necking failure of the material. Shear strain distribution has much to do with the failure of the material. The effects of the local strain rate on layered material plastic deformation were researched. High local strain rate corresponding with low Plastic flow capacity which can lead to Local strain concentration and the failure of the material.From the in situ tensile which based on DIC in micro scale, we o bserved the local strain distribution law of a particular interface area, The interface of the Ti and Al is one of the most vulnerable area to produce local strain concentration in the process of the plastic deformation of the Ti- Al layered composites.We observed crack initiation condition by in situ synchrotron radiation, the fracture mechanism is as follows: at first, deformation coordination of differences can easily lead to micro crack in the interface, along with not harmonious, the crack extended along the interface, Ti shape instability, interface crack expand t o Ti direction along with Al work hardening constantly. When the crack expand to the Ti layer to a certain degree, the deformation strengthening of the layer Al is over and Al entered the plastic instability. Ti layer crack tip get Al stress release, terminate the extension, until the cessation of Al layer of plastic instability. When the interface crack run through Al layer, the stress through the regional release and caused the stress concentration of adjacent layer, the extension of crack never stop until the final fracture of the materials.