Surface-Roughness-Induced Plasticity in a Biodegradable Zn Alloy

Improving plasticity has been an eternal theme of developing metallic materials. It is difficult to increase room-temperature elongation of metallic materials over 100% without sacrificing strength using existing methods. Herein, surface-roughness-induced plasticity (SRIP) is discovered in biodegradable Zn-0.4Mn alloy. Surprisingly, in the good surface range that meets the international standard ISO 6892, reducing surface roughness results in significant increase in plasticity without loss of strength. From unground to 5000# sandpaper ground states, the surface roughness R_a of the alloy decreases from 0.63 to 0.05 µm, while its room temperature elongation increases from 74% to 143%. SRIP is the synergistic result of increased microstructure damage tolerance and decreased surface roughness. It provides a new method for improving plasticity.