Effect of variations in Mn content on mechanical and corrosion characteristics of Cu-Al-Mn shape memory alloys

Abstract

In this work, the role of Mn on the shape memory effect and mechanical and corrosion behavior of Cu-Al-Mn shape memory alloys was studied. The composition of Al was fixed to 10 wt% while that of Mn was varied from 2 to 10 wt%. The strain recovery by SME was evaluated using the bend test, while the yield and ultimate tensile strength were obtained using the tension test. The corrosion behavior was studied using three different solutions: freshwater, substitute ocean water, and Hank's solution. The yield and ultimate tensile strength of Cu-Al-Mn alloys increased with Mn content up to 6%, which was attributed to grain refinement and precipitation hardening, while the fracture analysis showed mixed mode failure for all alloys. The corrosion behavior of Cu-Al-Mn alloys was modified due to the addition of Mn. With the increase in Mn content, the alloys displayed better corrosion resistance and lower corrosion rates. The corroded surface analysis tested in freshwater showed pitting corrosion, while Cu-Al-Mn alloy with low Mn content was tested in substitute ocean water. Hank's solution showed surface damage with an unstable surface layer.