Numerical and Experimental Investigations of Laser Metal Deposition (LMD) Using STS 316L

This study aimed to understand the effect of heat accumulation on microstructure formation on STS 316L during multilayer deposition by a laser metal deposition (LMD) process and to predict the microstructure morphology. A comprehensive experimental and numerical study was conducted to quantify the solidification parameters (temperature gradient (G) and growth rate (R)) in the LMD multilayer deposition process. During deposition, the temperature profile at a fixed point in the deposit was measured to validate the numerical model, and then the solidification parameters were quantified using the model. Simultaneously, the microstructure of the deposit was investigated to confirm the microstructure morphology. Then, a relationship between the microstructure morphology and the G/R was proposed using a solidification map. The findings of this study can guide the design of scanning paths to produce deposits with a uniform structure.

Antimony deposition onto Au(111) and insertion of Mg

Magnesium-based secondary batteries have been regarded as a viable alternative to the immensely popular Li-ion systems owing to their high volumetric capacity. One of the largest challenges is the selection of Mg anode material since the insertion/extraction processes are kinetically slow because of the large ionic radius and high charge density of Mg2+ compared with Li+. In this work, we prepared very thin films of Sb by electrodeposition on a Au(111) substrate. Monolayer and multilayer deposition (up to 20 monolayers) were characterized by cyclic voltammetry (CV) and scanning tunneling microscopy (STM). Monolayer deposition results in a characteristic row structure; the monolayer is commensurate in one dimension, but not in the other. The row structure is to some extent maintained after deposition of further layers. After dissolution of the Sb multilayers the substrate is roughened on the atomic scale due to alloy formation, as demonstrated by CV and STM. Further multilayer deposition correspondingly leads to a rough deposit with protrusions of up to 3 nm. The cyclic voltammogram for Mg insertion/de-insertion from MgCl2/AlCl3/tetraglyme (MACC/TG) electrolyte into/from a Sb-modified electrode shows a positive shift (400 mV) of the onset potential of Mg deposition compared to that of a bare Au electrode. From the charge of the Mg deposition, we find that the ratio of Mg to Sb is 1:1, which is somewhat less than expected for the Mg3Sb2 alloy.

Antimony deposition onto Au (111) and insertion of Mg

Magnesium based secondary batteries have been regarded as a viable alternative compared to the immensely popular Li-ion systems owing to its high volumetric capacity. One of the largest challenges is the selection of Mg anode material since the insertion/extraction processes are kinetically slow because the large ionic radius and high charge density of Mg2+ compared with Li+. We prepared very thin films of Sb by electrodeposition on an Au (111) substrate. Monolayer and multilayer deposition (up to 20 Monolayer) were characterized by cyclic voltammetry and STM (Scanning-Tunneling-Microscope). Monolayer deposition results in a characteristic row structure; the monolayer is commensurate in one dimension, but not in the other. The row structure is to some extent maintained after deposition of further layers. After dissolution of the multilayers of Sb the substrate is roughened on the atomic scale due to alloy formation, as demonstrated by CV and STM. Further multilayer deposition correspondingly leads to rough deposit with protrusion of up to 3 nm. The cyclic voltammogram for Mg insertion/de-insertion from MgCl2/AlCl3/Tetraglyme (MACC/TG) electrolyte into/from Sb modified electrode shows a positive shift (400 mV) of the onset potential of Mg deposition compared to that at bare Au electrode. From the charge of Mg deposition, we find that the ratio of Mg to Sb is 1:1; and this somewhat less than expected for the Mg3Sb2 alloy.