Study On Laser Deposited TC4/TC11 Gradient Structure Process

In this paper,TC4/TC11 dual alloy structures were prepared by laser deposition technology.First,directly deposited TC4/TC11 dual alloy were investigated by optical microscopy(OM),scanning electron microscopy(SEM),micro-hardness tester and universal testing machine.Microstructure and tensile fracture of the specimens were observed,while the micro-hardness and tensile properties were tested and analyzed.Then further research on multi-layer transition TC4/TC11 dual was conducted,where its transition layer number was 0 layer,1 layer and 3 layer respectively.The influence of the transition layer number on the microstructure and mechanical properties is also discussed.The results show that microstructure on the side of TC4 titanium alloy is larger than those on TC11 titanium alloy side whether deposited or treated by solid solution and aging treatment.But not broken in the transition zone,which indicates that the transition interface is not the weak part of the TC4/TC11 alloy.The micro-hardness of TC4/TC11 dual alloy direct transition specimen shows a rising trend from TC4 titanium alloy area to TC11 titanium alloy areaThe transition layer number had great influence on the microstructure of the interface of TC4/TC11 alloy.With the number of layers increasing,the microstructure distribution difference of TC4/TC11 alloy interface decreases gradually,and the microstructure tended to be homogeneous.The tensile fracture of gradient-transited TC4/TC11 alloy specimens is ductile fracture at room temperature after stress annealing treatment.And with the transition layers increasing,the dimples are bigger and deeper.The tensile strength increases significantly,and the plasticity becomes better.Different heat treatment regimes have a significant influence on the microstructure of the TC4/TC11 alloy whose number is 0.The heat treatment temperature has little effect on the microstructure of the TC4/TC11 alloy interface with the transition layer of 3,which is related to the increasing number of transition layers.