Additive manufacturing of refractory high-entropy alloys: A critical review of fundamentals and advances
Ali Mohammadnejad, Manyou Sun, Naga Aditya Yarlapati, Mahyar Hasanabadi, Esmaeil Sadeghi, Paria Karimi, Yu Zou, Ehsan Toyserkani
Abstract
Refractory high entropy alloys (RHEAs) hold immense potential as superior alternatives to existing superalloys in the nuclear, energy, and aerospace industries. However, the fabrication of refractory alloys and RHEA parts has long been hindered by challenges associated with brittleness and a high oxidation rate. Fortunately, additive manufacturing (AM) presents a transformative opportunity for these materials. In contrast to conventional methods, AM offers the advantage of fabricating intricate and near-net-shape parts without restrictions caused by high melting points and severe high-temperature oxidation of refractories. Consequently, numerous studies have explored the feasibility of printing RHEAs for various applications, with the majority demonstrating improved mechanical properties and the ability to engineer microstructures and compositions. Nevertheless, challenges exist in the AM of these alloys, including the formation of microcracks, pores and elemental loss, impeding the realization of their full potential. This paper aims to delve into the fundamentals of RHEAs, encompassing the preparation of RHEA powders, the printability of these alloys and a critical assessment of their properties. To overcome the RHEA printing issues, this paper reviews the integration of thermodynamic modeling, phase diagram calculations, and numerical modeling, followed by an evaluation of the potential applications of RHEAs based on their properties and costs.