Research On Microstructure And Deformation Texture Of Ultrafine Ti/Zr Laminated Composite Material

Multilayered metallic composite refers to a composite material composed of the same or different metals in a certain unit layer thickness.The metal laminated composite material has the characteristics of high strength,low cost and wide application by combining the advantages of each component metal in physical,chemical and mechanical aspects.Most of the current research status is limited to the cubic system,and the research on the dense hexagonal system is relatively limited.In this paper,a laminated metal material plate of a close packed hexagonal metal Ti and a metal Zr having the same crystal structure was studied.Ti/Zr with a sub-micron unit thickness was prepared by accumulative roll-bonding and subsequent cold rolling techniques.Two kinds of Ti/Zr laminated were preparing for the metal laminated composite plate:the initial metal of the pure metal Ti and Zr is 50 ?m and 50 ?m in thickness,respectively.The laminated composite plate prepared from the materials were named Ti/Zr-50 ?m and Ti/Zr-25?m.Taking these two composite plate as the research object,the microstructure of the lateral rolling surface of the layered composite material and the composition distribution at the heterointerface were obtained by scanning electron microscopy(SEM)and energy spectrum analyzer(EDS).The microstructure of each metal layer of the layered composite plate was obtained by electron microscopy(TEM).The macroscopic mechanical properties of the composite plate were tested by an electronic universal tensile tester.The X-ray diffractometer(XRD)was used to obtain the composite plate.The texture distribution and evolution of each of the two closely packed hexagonal metals.In the Ti/Zr layered composite plate,the Ti layer and the Zr layer are well bonded during the ARB process.From the first cycle,the two plate have undergone different degrees of deformation.The Ti layer is necked more severely than the Zr layer,and there are shear bands running through laminated composite.In the end,the two metals have different degrees of necking,fracture,and even separation.The mechanical properties of the Ti/Zr laminated composite plate are well.After the post-rolling composite sheet is subjected to subsequent cold rolling,the strength is greatly improved,and the elongation rate is decreased.The grain sizes of the Ti layer and the Zr layer are both on the order of nanometers.The Ti layer in the composite plate has the following typical features,specifically:the grains are approximately equiaxed,some of the grains have a large number of dislocations inside,some have no dislocations inside,and some dislocations are wrapped around the grain boundaries,forming dislocation cells.And Ti of the FCC crystal structure is found in the sample.There are a large number of dislocations in the Zr layer,some dislocations form a subgrain boundary,and some large crystal grains have a low dislocation density.The mixed microstructure of Ti and Zr in the composite plate gives the composite plate high strength and good plasticity.During the rolling and subsequent cold rolling,the texture of the composite plate changed:in the Ti/Zr-50 ?m composite plate,the pure titanium is the {0001} basal double-peak texture,and the {1120}<1010>texture appears after the rolling.As the thickness of the unit layer becomes thinner,the texture component is strengthened until it is equivalent to the strength of the {0001} basal double-peak texture.Pure zirconium is a {0001} basal texture.As the unit layer becomes thinner,the strength is weakened.In the Ti/Zr-25?m composite sheet,the titanium layer is a {0001} basal double-peak texture,and the {1120}<1010>texture appears after the rolling.As the thickness of the unit layer becomes thinner,the texture component is strengthened until it is equivalent to the strength of {0001} basal double-peak texture.The texture type of pure zirconium is{0001} basal double-peak texture,and the {1120}<1010>texture appears after the rolling.As the thickness of the unit layer becomes thinner,the strength of the{1120}<1010>texture component is basically unchanged,and the abnormal changes of the texture components.It is related to the generation of the shear band.