Powder Metallurgy TC11 Titanium Alloy Via Hot Isostatic Pressing:Preparation,Microstructure and High-Cycle Fatigue Property
Powder metallurgy through hot isostatic pressing(HIP)route,which is a promising near-net forming method,can fabricate high-performance titanium alloy components with complex structure for applications in the aerospace field.In this study,TC11 pre-alloyed powder was made by electrode induction melting gas atomization method,and the as-received powder was characterized.The powder compacts were HIP at 940℃/140 MPa/3 h from the pre-alloyed powder.The microstructure of as-HIPed powder compact was observed by OM and SEM,and the mechanical properties were evaluated by tensile,impact and high-cycle fatigue tests.The effect of residual micro-pores induced by the hollow powder with gas bubbles on fatigue life of as-HIPed powder compact was also investigated.The results show that the TC11 powder compact is approaching to full density,and the microstructure is fine and homogeneous.The quasi-static mechanical properties of as-HIPed powder compacts are close to or even better than those of wrought alloys.The rotating bending fatigue strength is about 590 MPa at 107 cycles.However,the duality of the high-cycle fatigue S-N curve is observed.The micro-pores located at the surfaces of specimens will preferentially become crack initiation sites under fatigue loading conditions,which will further significantly reduce the high-cycle fatigue life of the powder compacts.
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