Magnetostrictive improvement in Er-doped biodegradable Fe81Ga19 alloys manufactured by selective laser melting

Abstract

In this study, rare earth Er was introduced into magnetostrictive Fe–Ga alloys by selective laser melting (SLM) technique for the first time in order to tailor the microstructure and thereby the magnetostrictive properties. The results showed that the rapid solidification of SLM process not only retained the disorder phases but also promoted the solid solution of partial Er into Fe–Ga matrix which increased the lattice parameters. Moreover, the rest of Er distributed at the grain boundaries along the temperature gradient and prevented the lateral expansion of matrix grains, leading to columnar grains with preferred orientation in {100} direction. Consequently, the magnetostriction coefficient of the Er-doped Fe81Ga19 alloys was improved up to 92 ppm with an Er content of 0.6 at.%, representing a 40% enhancement compared to Fe81Ga19 alloy. But excessive Er resulted in the formation of GaEr intermetallic phase, which was adverse to Ga–Ga pair structure and magnetostriction. The Fe81Ga19Er0.6 alloy also presented acceptable cytocompatibility and slightly accelerated degradation due to the galvanic corrosion between Er phase and Fe–Ga matrix. These findings indicated the potential of the Er-doped Fe81Ga19 alloys prepared by SLM as future magnetostrictive implants in biology and medicine.

Keywords

• Fe–Ga–Er alloys
• Selective laser melting
• Grain orientation
• Magnetostriction
• Biodegradation