Selective laser melting (SLM) of pure molybdenum encounters all the difficulties of SLM metals due to its intrinsic properties (high melting point, high ductile-to-brittle transition temperature and high surface tension). In this work, we studied the influence of key factors such as powder morphology and processing parameters on SLM fabricated pure molybdenum. Pure molybdenum with a relative density of 99.1% was fabricated by SLM using optimized processing parameters. The formation mechanisms for densification behavior and crack growth behaviors are systematically analyzed. Electron backscattered diffraction analysis indicates that the interlocking grain boundary structure and stretch columnar grains can increase bonding force and inhibit crack growth. The balling and cracking can be reduced by adding support structure and suppressing oxygen content. The hardness of SLM-fabricated molybdenum exceeding 260 HV, which is 30–37% higher than Mo prepared by conventional manufacturing methods, mainly attributed to the fine grains and dislocation strengthening in the SLM process. The bending strength of SLM-ed Mo reached 280 ± 52 Mpa. The fracture mode of SLM Mo was intergranular. This study provides a new route for the fabrication of refractory metals with a complex structure.

Additively manufactured tungsten and its alloys have been widely used for plasma facing components (PFCs) in future nuclear fusion reactors. Under the fusion process, PFCs experience a high-temperature exposure, which will ultimately affect the microstructural features, keeping in mind the importance of microstructures. In this study, microhardness and electron backscatter diffraction (EBSD) techniques were used to study the specimens. Vickers hardness method was used to study tungsten under different parameters. EBSD technique was used to study the microstructure and Kikuchi pattern of samples under different orientations. We mainly focused on selective laser melting (SLM) parameters and the effects of these parameters on the results of different techniques used to study the behavior of samples.

In this study, fully dense tungsten samples were additively manufactured and the micro-structure behavior was studied. A crack network with a spacing of 20μm up to 100μm was found in the designed samples. It was noticed that the laser scanning approach, which could customize the microstructure, affected the crack behavior in manufactured tungsten[1]. Different additive parameters were adopted to study the microstructure properties, but it was revealed that cracking is practically irresistible in AM (additive manufacturing). It might be achieved that cracking chain assembled because the cracks appeared in each laser fused path and then analogous in the surface-by-surface structure course.

This article is a comparative study of tungsten (W) and molybdenum (Mo) samples manufactured by selective laser melting (SLM).Under the processing parameters different microstructural and mechanical properties like strain energy density, micro-hardness and surface morphology were investigated. Before the preparation of samples the SEM and XRD images were taken to calculate the size of micro particles of both the samples. These samples were further investigated by OM(optical microscopy),SEM(scanning electron microscope),EBSD(electron backscattering diffraction) and Vicker hardness to study the crystallographic structure, hardness, grain boundaries to understand a brief comparison between these two fourth group elements. It was identified as the cause of a very prominent structure with cracked features and a residual remains. During processing, different processing factors were examined, which separates at the edges of the grain, thereby creating thermal cracks. This due to the low eutectic melting compared to the matrix phase. These factors also result in a higher Ductile-to-Brittle Transition (DBTT). Later, during rapid cooling from the melting point, a combination of cracks with hot cracks on the borders of solid grain grains and cold cracks near weak grain edges forms a cracked network, which is often found in tungsten and molybdenum refined SLM. Neither does a very hot substrate plate prevent the formation of cracks in the metals formed by processing parameters. These materials are appropriate for high temperature up to more than 2000⁰C such an analytic and inner wall constituents of fusion reactor or experiments. Parameters like laser power, scan speed, hatching space and the thickness of the powder layer are analyzed to achieve the high density samples. Three-dimensional printing is changing the way we make things in almost every industry, from cars to medical equipment to biotech.3D printing to prototype one of the most critical enabling technology in a building, the heat exchanger. In comparison to current designs, this next-generation heat exchanger weighs 20% less, performs 20% better, and can be produced much faster.