Effect of Alloying Mn by Selective Laser Melting on the Microstructure and Biodegradation Properties of Pure Mg

Abstract

This work studied the effect of alloying Mn by selective laser melting on the microstructure and biodegradation properties of pure Mg. The grains in the microstructure were quasi-polygon in shape. The average grain size was similar (~10 μm) for the SLMed Mg-xMn with different Mn contents. The XPS spectra of the corrosion surface showed that alloying Mn into Mg by SLM produced a relatively protective manganese oxide film, which contributed to decreasing the biodegradation rate. All the results of the electrochemistry test, immersion test and the corrosion surface morphologies coincided well. The SLMed Mg-0.8Mn had the lowest biodegradation rate. When Mn content was more than 0.8 wt.%, the influence of the undissolved Mn phase on the decrease of the biodegradation resistance counteracted the influence of the relatively protective manganese oxide layer on the increase of the biodegradation resistance.

Extrusion-based 3D printed magnesium scaffolds with multifunctional MgF2and MgF2–CaP coatings

“…3f and Fig. 4f), as also observed by other researchers [56,57], which was probably caused by the large differences in the physical and mechanical properties between the Mg(OH) 2 film and MgF 2 [40] as well as the evolution of hydrogen during the fluoride conversion treatment.…”

“…2e). However, the average grain size of the fabricated Mg scaffolds was larger than that of laser AM Mg [57] due to rapid cooling involved in the latter.…”

Additive manufacturing of magnesium and its alloys: process-formability-microstructure-performance relationship and underlying mechanism

“…For instance, Shuai et al found that a 1 wt.% of Al additive remarkably reduced the grain size of LPBF-processed Mg-3Zn alloy from (21.6 ± 2.6) µm to (10.5 ± 1.9) µm, and with increasing the Al content to 7 wt.%, the grain size was further decreased to (6.8 ± 1.5) µm [79]. However, it is reported that the Mn addition had little impact on grain refinement [94]. The above phenomenon is ascribed to the undercooling degree variation with chemical composition addition.…”

“…Chemical composition of material is another key factor affecting grain size. Up to now, the effects of Al [43,79], Mn [93][94][95], Zn [44], Cu [92,96], Ce [97], Dy [98] on the grain size of additively manufactured magnesium alloys have been investigated. The results demonstrated that the addition of Al, Cu, Zn, Ce and Dy can significantly refine the grains, and the grain size decreases monotonically with the content increase of these elements.…”

A review of additive manufacturing of Mg-based alloys and composite implants

“…The as-fabricated scaffolds showed improved biodegradation resistance of 0.17 ml/ cm 2 •day compared with the as-extruded and as-cast counterparts of 0.3 ml/cm 2 •day. Xie et al [104] investigated SLMed Mg-xMn with various content of Mn. The XPS spectra of the corrosion surface exhibited that alloying manganese into magnesium by SLM produced a protective film of manganese oxide, which reduced the biodegradation rate.…”