Effect of Scan Length on Densification and Crystallographic Texture Formation of Pure Chromium Fabricated by Laser Powder Bed Fusion

Processing of pure chromium (Cr) encounters substantial challenges due to its high melting point and intrinsic brittleness. Although laser powder bed fusion processing (LPBF) offers a novel processing approach by reaching the temperature required to melt pure Cr, the high ductile-to-brittle transformation temperature (DBTT) of pure Cr prevents the density of the as-built Cr component from reaching the level of industrial acceptance. This study focuses on raising the quality of the as-built pure Cr components to the industrial level while considering the effect of scan length on densification and crystallographic texture. It was found that short scan length induced by feature size improved the density of as-built specimens while strengthening the texture suggesting uniform heat distribution and lower thermal gradients as a result of short time intervals in scanning tracks and layers. It was discovered that cracking caused by residual stress was detrimental to densification due to the DBTT characteristic of pure Cr, which was localized at high-angle grain boundaries (HAGBs) with high misorientation. The decrease in density and misorientation of HAGBs owing to the increase in grain size and texture strength, respectively, improved the density of as-built Cr up to 97.6% and altered its mechanical properties. Therefore, these findings offer new insight into the LPBF processing of metals with high DBTT characteristics.

Doping Effect of Lead(II) on Structural and Optical Properties of Chromium Oxide Nanoparticles

In this work, the effects of doping post transition metal (Pb2+) on the structural, morphological, elemental and optical properties of pure chromium oxide nanoparticles are reported. The structural and morphological properties were examined by X-ray diffraction and scanning electron microscopy (SEM). The elemental composition of the prepared nanoparticles were estimated from energy dispersive X-ray (EDX) absorption spectra. The band gap energies of the prepared nanoparticles (4.72-3.78 eV) obtained from UV-vis absorption spectroscopy is higher than that of bulk Cr2O3 (3.3 eV), which ensures that the prepared nanoparticles were successfully synthesized in the nano-region.