Corrosion Behaviour of Ti-based Bulk Metallic Glass Matrix Composites

Abstract

(Ti0.5Ni0.5)80Cu20 metallic glass composite samples with 3mm diameter were prepared by the levitation suspend melting-water cooled Cu mold process, microstructure of the alloy was characterized. The potential dynamic polarization curves in the different media were tested by electrochemical workstation in a three-electrode system, meanwhile, the electrochemical corrosion morphology and corrosion products were analyzed and characterized. The results show that the microstructure consists of amorphous matrix and shape memory crystal phase, exhibits gradient microstructure in casting process of temperature gradient, random dense pile of amorphous structure is formed in the edge area due to fast cooling rate, the main precipitation phase is overcooling austenite phase in the core area. In artificial seawater and simulated body solution (PBS), the alloy exhibits good corrosion resistance. Compared with crystalline TC4 alloy, the alloy exhibits high free corrosion potential that shows low corrosion thermodynamics tendency and has low corrosion current density as well as high polarization resistance that indicates low dynamic corrosion rate. Due to the low activity anion concentration in PBS solution, the alloy exhibits more excellent corrosion resistance than in artificial seawater. No pitting corrosion pits and corrosion products were found after electrochemical corrosion. The oxide film in the edge area is more compact and uniform than in the core area as well.

Keywords

• bulk metallic glass
• shape memory phase
• microstructure
• corrosion behaviour