Effect of Substrate Plate Heating on the Microstructure and Properties of Selective Laser Melted Al-20Si-5Fe-3Cu-1Mg Alloy

Selective Laser Melting of Commercially Pure Molybdenum by Laser Rescanning

Commercially pure (cp) molybdenum (Mo) is one of the high-temperature materials of immense potential. It has a body-centered cubic (bcc) structure so it is hard to fabricate using nonequilibrium processes such as the selective laser melting (SLM) without the formation of cracks due to its inherent brittleness. This study deals with the fabrication of dense and near crack-free cp-Mo samples produced by the SLM. The laser scan strategy is adjusted from a single scan to a double scan to reduce the solidification cracks. Samples produced with a laser double scan strategy show a density of ∼99% with a hardness of ∼222 HV.

Metallic Coatings through Additive Manufacturing: A Review

Metallic additive manufacturing is expeditiously gaining attention in advanced industries for manufacturing intricate structures for customized applications. However, the inadequate surface quality has inspired the inception of metallic coatings through additive manufacturing methods. This work presents a brief review of the different genres of metallic coatings adapted by industries through additive manufacturing technologies. The methodologies are classified according to the type of allied energies used in the process, such as direct energy deposition, binder jetting, powder bed fusion, hot spray coatings, sheet lamination, etc. Each method is described in detail and supported by relevant literature. The paper also includes the needs, applications, and challenges involved in each process.

The surface structure, stability, and catalytic performances toward O2 reduction of CoP and FeCoP2

The systematic atomistic level investigation of low-index surface structures, stabilities, and catalytic performances of CoP and FeCoP₂ towards the O₂ reduction reaction (ORR) is vital for their applications. Employing first-principles calculations, it is revealed that CoP and FeCoP₂ present the same surface stability in the order of (101) ≈ (011) > (111) > (001) > (110) > (010) > (100). They also possess a similar Wulff equilibrium crystal shape with (101) and (011) exposing the largest surface area. From the electronic view, FeCoP₂ presents improved electronic conductivity compared with CoP. From the energy view, whether FeCoP₂ delivers improved electrocatalytic activity toward the ORR with respect to CoP depends on the reactive surfaces and sites. Among the 4 surfaces considered, only CoP(101), FeCoP₂(101) and FeCoP₂(011) delivered ORR performances theoretically when the bridge metal-metal site acts as the reactive center, which makes CoP(011) the only exception. CoP(101)-b_Co-Co and FeCoP₂(011)-b_Fe-Co exhibit a larger thermodynamic limiting potential than FeCoP₂(101)-b_Co-Co, suggesting their higher performances toward the ORR. The last step of HO* desorption as the rate-limiting step accounts for 3/4. The third step of transformation from O* to HO* as the most sluggish step accounts for 1/4. The work function, d-band center, Bader charge, and electronic localization function calculations are performed to reveal the HO adsorption nature. The present work provides fundamental insight into the effect of Fe doping into CoP, the determination of the catalyst surface and the key species adsorption nature to guide the rational design of high-performance materials.