In-situ alloying in laser-based additive manufacturing processes: A critical review

The growing need to develop cost-effective and efficient alloys requires enhancing the flexibility of the current production methods. Additive manufacturing (AM), as an emerging technology, has re-shaped the manufacturing strategies and largely influenced the industrial production lines. The feedstock, the main concern with regard to the powder-based AM methods, are mostly in the form of pre-alloyed powders. Pre-alloyed powders have a narrow composition range, suffer from limited availability and are expensive, making additive manufacturing of new alloys inflexible and costly. A growing number of works in the literature are dedicated to AM in-situ alloying, i.e. employing pure elemental blends as opposed to pre-alloyed ones for producing samples using additive manufacturing. This strategy gives added flexibility to the AM methods by benefiting from the laser local energy and paves the way towards an on-demand alloy design framework that is proportionate to the growing needs of the industry. This review is intended to shed light on the key components of AM in-situ alloying process, from initial blend preparation to requirements for the final composition homogeneity.