Resolving the porosity-unmelted inclusion dilemma during in-situ alloying of Ti34Nb via laser powder bed fusion

Electron Beam Melting of Niobium Alloys from Blended Powders

“…This partially explains why a difference in particle size before and after heat treatment could not be discerned, although an increase in matrix W concentration was observed. Alterative techniques such as x-ray computed tomography (CT) have been used to quantify unmelted Nb inclusions in a Ti-Nb alloy powder blend (Ti-34Nb) with a resolution of 5 µm [ 30 ] though commercial CT systems generally are not capable of penetrating a Nb-W alloy with satisfactory voxel resolution (<10 µm).…”

“…Blended powder feedstocks for EB-PBF can expedite material development and reduce preparation costs, but interdiffusion between constituents remains a challenge [ 26 , 27 , 28 ]. Previous work involving L-PBF blended refractory powders with large melting point gaps have been published recently [ 29 , 30 ]. These studies suggest that there is a narrow processing window for achieving a fully solutionized microstructure (high energy requirement) without inducing keyhole porosity (low energy requirement).…”

Recent progress and scientific challenges in multi-material additive manufacturing via laser-based powder bed fusion

“…processing parameters (e.g. scanning speed (Kuo et al 2020;Huang et al 2021), hatch distance (Kuo et al 2020), and laser power (Huang et al 2021), optimising scanning strategies (Nadammal et al 2021;Sing and Yeong 2020), and using a top-hat laser profile (Huang et al 2021)). If the melting points of the two materials are similar, the above measures are suitable for suppressing the occurrence of defects due to the lack of fusion.…”

Modelling of grain structure using cellular automata-finite element method for additive manufacturing of metals

“…Figure 4-10 shows the difference in melt pool geometry. The experimental result show an approximated melt pool width to average around 1000 m and 200 m for case 1 and 2 respectively [108]. In comparison, the FEM simulation found the melt pool width to be 1070 m and 170 m for case 1 and 2 respectively.…”

“…The difference in melt pool sizes can lead to different grain sizes and was observed in the EBSD data where the average grain width of case 1 is 243 m and case 2 is 71 m [108]. The CA model found the average grain width to be 133 m and 81 m for case 1 and 2 respectively.…”