Influence of Micro/Nano-Ti Particles on the Corrosion Behavior of AZ31-Ti Composites

Adding Ti particles to magnesium alloy simultaneously enhances its strength and ductility. However, how these particles influence on Mg alloy's corrosion performance is seldom reported. The corrosion behavior of AZ31-Ti composites containing titanium nanoparticles (1.5 and 5 wt%) and micron particles (10 wt%) prepared by powder metallurgical in 3.5 wt% NaCl solution was investigated. The results indicate that Ti particles serve as the primary location for the cathodic hydrogen reduction reaction, resulting in intense galvanic corrosion between the Ti and Mg matrix. Ti nanoparticles distributed at the interface of the original AZ31 powder were in a discontinuous mesh structure, thus failing to act as a barrier against corrosion. The corrosion products with the existence of numerous cracks gradually peel off during the corrosion process and cannot protect the matrix. The average corrosion rate Pw of AZ31, AZ31-1.5%Ti, AZ31-5%Ti, and AZ31-10%Ti after 7 days of immersion is 27.55, 105.65, 283.67, and 99.35 mm/y, respectively. Therefore, AZ31-Ti composites can be considered as potential candidates for degradable fracturing tools. Otherwise, it is recommended to improve their corrosion resistance through surface treatment.