Microstructure And Properties Of Ni_p-Ti/Al₃Ti Laminated Composites

In recent years,Ti/Al₃Ti layered composites have been designed by scholars following the shell structure.It is a kind of materials that combines the ductile metal Ti with the brittle intermetallic compounds,which have excellent properties such as high specific strength,low density and impact resistance.Based on the materials,Ni powder was added to the layered composites to form Ni-Al intermetallic compounds between the layers.The microstructure of the successfully prepared Ni_p-Ti/Al₃Ti layered composites was observed,and the effect of Ni distribution on the microstructure was analyzed.Then the mechanical properties of the materials were tested.Ni_p-Ti/Al₃Ti layered composites were successfully prepared by vacuum hot pressing sintering.The reasonable process parameters were determined as 645?vacuum holding for 6 hours and initial pressure of 3MPa.Then the microstructure of Ni _P-Ti/Al₃Ti layered composites was characterized.XRD and EDS results show that Al₃Ti and Al₃Ni intermetallic compounds are fully formed by the reaction of Al layer during sintering process.It is found in SEM that Ni is enriched in the intermetallic compound layer,mainly around the interface and the center line.And it has a great influence on the densification of Al₃Ti.In the performance test,the density of Ni_p-Ti/Al₃Ti layered composite was determined to be 3.71g/cm~3.The microhardness distribution has periodic symmetry.In the tensile test,the tensile strength of Ni_p-Ti/Al₃Ti layered composites is 258.97MPa.The material exhibits anisotropy in the compression test.During the transverse compression process,large plastic deformation occurs on the whole,and the failure strain is as high as 70%.During longitudinal compression,the material first exhibits brittleness and then toughness,and the compressive strength is 491.85MPa at the brittle stage.In the three-point bending test,it also shows anisotropy,with the transverse bending strength of242.66MPa and the longitudinal bending strength of 428.37MPa.In the fracture toughness test,the K_?C of Ni_p-Ti/Al₃Ti layered composites is 12.76MPa·m^1/2.In fracture analysis,the fracture forms of materials are consistent.Brittle fracture and ductile fracture occur simultaneously.Plastic deformation of metal layer and intermetallic compound layer intergranular fracture occur during failure.Due to the special lamination structure of layered composites,the cracks in the intermetallic compound layer are deflected and terminated by the influence of the nearby metal layer.There is a special step phenomenon on the curve of mechanical properties,and the overall mechanical properties have been improved.