Microstructure and surface texture driven improvement in in-vitro response of laser surface processed AZ31B magnesium alloy

The present work explored effects of laser surface melting on microstructure and surface topography evolution in AZ31B magnesium alloy. Thermokinetic effects experienced by the material during laser surface melting were simulated using a multiphysics finite element model. Microstructure and phase evolution were examined using scanning electron microscopy, X-ray diffraction, and electron back scatter diffraction. Surface topography was evaluated using white light interferometry. The interaction of surface melted samples with simulated body fluid was monitored by contact angle measurements and immersion studies up to 7 days. Laser surface melting led to formation of a refined microstructure with predominantly basal crystallographic texture. Concurrently, the amount of beta phase (Mg17Al12) increased with an increase in the laser fluence. beta phase preferentially decorated the cell boundaries. In terms of topography, the surface became progressively rougher with an increase in laser fluence. As a result, upon immersion in simulated body fluid, the laser surface melted samples showed an improved wettability, corrosion resistance, and precipitation of mineral having composition closer to the hydroxyapatite bone mineral compared to the untreated sample. (C) 2020 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Automated summary

The study investigated the effects of laser surface melting on microstructure and surface topography evolution in AZ31B magnesium alloy, revealing that laser surface melting led to the formation of a refined microstructure and a progressively rougher surface. This resulted in improved wettability, corrosion resistance, and precipitation of mineral closer to hydroxyapatite in simulated body fluid for the samples treated with laser surface melting compared to untreated samples.