Electrical Discharge Machining of Biomedical Nitinol Alloys and the Resulting Fundamental Relationship of Microstructure-Property-Function

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The research objective of this proposal is to understand the basic relationship between machining conditions, white layer (that is, recast layer), and fatigue and corrosion by electrical discharge machining of biomedical Nitinol alloys by bringing together complementary international research and education expertise. It will test the hypothesis that electrical discharge machining using minimum discharge energy is a very competitive process compared to mechanical machining to economically fabricate delicate burr-free Nitinol microstructures with high aspect ratio and excellent surface finish. The research approaches are to: (1) explore the process capability in electrical discharge machining of biomedical Nitinol alloys to establish a basic relationship between processing conditions and surface integrity; (2) determine whether the white layer is metastable nano-quasicrystal using transmission electron microscopy and x-ray diffraction; (3) clarify the fundamental role of process-induced surface integrity, white layer in particular, on fatigue and corrosion performance; and (4) reveal material erosion mechanism and microstructural evolution in electrical discharging via a multiphysics process simulation approach with the capability of material ablation.The research results will have a wide spectrum of impacts on machining of a broad range of other difficult-to-cut materials including titanium, Inconel, stainless steel, and hardened alloys. The sound sustainable practices in electrical discharge machining of metallic biomaterials can bring business value to biomedical device industry as well as tool, gas turbine, chemical and oil industries. The project will establish a synergistic education network between the University of Alabama and Aachen University to train the next cadre of ?whole-brain? students in the global context. The collaborative network will also provide an express way for fast technology transfer from fundamental research to industrial practices.