Multi-principal High Entropy Alloy Research Articles

Correlation between special bud-shaped area and molten pool flow in laser cladding high-entropy alloy on TC4 surface

Compared with the single principal component composition of traditional alloy materials, multi-principal high-entropy alloys (HEAs) tend to cause non-uniform distribution of coating elements. In this paper, an experimental study of laser cladding of HEA coating on the surface of TC4 is carried out. In observing the morphology of the cladding layer, it is found that there are special bud-like areas where Ti element accumulate abnormally at the bottom of the cladding layer. Because it has apparent traces of molten pool agitation, it is inferred that its cause is closely related to the flow of the molten pool. The mechanism of the non-uniform distribution of elements in the laser cladding layer of HEA was studied from the perspective of molten pool flow. From the cross-section and the longitudinal-section of the molten pool, the influence of the molten pool flow on the Ti element's abnormal accumulation in the special bud-shaped area is explored. It was revealed that, a Marangoni circulation is formed at the bottom of the melt pool during laser cladding, under which the element Ti is stirred into the melting pool due to its low melting point, creating a large accumulation of elements.

Study of Solidification Microstructures of Multi-Principal High-Entropy Alloy FeCoNiCrMn by Using Experiments and Simulation

The microstructures and the solidification processes simulation of multi-principal high-entropy alloy FeCoNiCrMn were studied by using both experimental and computational approaches. The microstructures were identified by methods of XRD, SEM and EDS. The solidification process was simulated by Scheil-Gulliver solidification model. The alloy mainly forms a single FCC solid solution, but Mn atoms, as well as Ni atoms tend to be enriched in residual liquid phase during the solidification process. These atoms show interdendritic segregation. Present experimental results and computational results are supported each other well.

Explore the possibility of forming fcc high entropy alloys in equal-atomic systems CoFeMnNiM and CoFeMnNiSmM

The multi-principal high-entropy alloys (HEAs) are promising new alloys. However, it is a challenge to screen out the suitable composition from the diverse combinations. Referring to the prototype AuCu3 with AB3-L12 structure, where it becomes a face-centered cubic (fcc) structure if element A and B are the same element, the site occupying tendencies of the elements and thermodynamic functions are predicted by using the sublattice model supported with first-principles total energy calculations. By considering the Gibbs energy of formation and the configurational entropy, the fcc HEAs in available literatures are examined, and the results of the quinary system with equal-atomic composition CoFeMnNiM and the hexbasic system with equal-atomic composition CoFeMnNiSmM are reported, respectively, where the element M is selected from the rest of the periodical table. When M=Cr, Zn, Ru, Rh, Pd, Re, Os, Ir, or Pt in the quinary systems CoFeMnNiM and when M=Ru, Pd, or Pt in the hexbasic systems CoFeMnNiSmM, respectively, the alloys are recommended to be potential fcc HEAs. The new approach opens a new way to mine the rich ores of HEAs.