Study On Microstructure And Deformation Mechanics Of Ti-Al Metal Laminate

In order to study the deformation behavior and evolution of microstructure inlaminated metal composites, and explore the effect of the macrostructure on thetoughening mechanism of composite materials, layered Ti-Al, Ti-(SiCp/Al)composites have been fabricated by hot press-rolling. Optical microscope, scanningelectron microscope, transmission electron microscope were used to observe themicrostructure and interface structure of Ti-Al. Different systems layered metalcomposites were evaluated by tensile test at room temperature. Deformation andfracture processes of layered Ti-Al composites under different strain states wereinvestigated with in-situ tensile experiments.The local texture of the laminated metalcomposites were measured by EBSD.Thickness ratio of Ti sheet and Al sheet in layered Ti-Al composite is1:2,1:1,2:1, Ti-(SiCp/Al) composite with three different SiCp volume fraction(3%,5%and10%), were fabricated by hot press and rolling through alternating layers of twomaterials. SEM microstructure analyses show layered Ti-Al composites which havea thickness ratio of1:1have the most uniform thickness of each component, and theinterface is flat, seamless. By XRD and EBSD analysis, layered Ti-Al compositeexhibited mainly basal texture, and the texture of Al is {111}<110>.The original Ti layer and different thickness ratio of layered Ti-Al compositehad been tested by tensile testing, the results showed that: the yield strength, tensilestrength and elongation was increased with the increase of thickness ratio, thicknessratio of laminated metal composites from1:1to2:1, the tensile strength increased to365MPa from221MPa, elongation increased from24%to37%. For different SiCpvolume fraction of Ti-(SiCp/Al), when the volume fraction of SiC particles reaches10%, the yield strength reaches277MPa, tensile strength reaches363MPa, yieldstrength and tensile strength increased by more than30%, but it still has25%elongation.By in-situ tensile test, observed surface topography of different thickness ratiosof layered Ti-Al composite until fracture in the deformation process, they are similar,at first Al layer generated slip bands, Ti layer produced embossed, followed cracksgo through the Ti layer, Al layer occured necking and the interface generateseparation, finally leading to the fracture. Because of the interface layer and the Al layer, partial rupture in Ti layer does not cause the rupture of Laminated metalcomposites, so that layered Ti-Al composites have good strength and ductility.The cross-section of layered Ti-Al composite in different strain area is analysisedby EBSD, with the deformation increases, fine grains began to appear in small strainzone at the interface, while the maximum deformation area, small grains also appearin location far away from the interface. Made texture analysise of Ti in as-rolled Ti-Al sheet in different strains,as the strain increases, the basal texture type remainsunchanged, and <1010>//RD preferred orientation gradually weakend,<1120>//RDtexture gradually strengthen.By combining DIC and in-situ tensile tests based OM, when the strain of layeredTi-Al composite increased to0.4, from the local stress and strain field graph, we cansee,formed a strip along the thickness direction, observed to have similar morphologyresults in deformation of the composite by in-siti tensile test.