The development of new alloys, in general, is an iterative, complex, and costly process. Considerable advancements in high-performance computer modelling and automated characterisation techniques have helped reduce the overall development time. Despite these advances, fabricating experimental samples remains tedious and time-consuming. In the past few years, notable improvements in manufacturing technology, such as multi-material additive manufacturing, have enhanced the efficiency and precision of the fabrication process. This study presents findings from a novel high-throughput screening approach to alloy development, which utilises a directed energy deposition additive manufacturing process with a plasma arc and different powders as feedstock materials. Austenitic stainless steel (ASS) and modified low-carbon steel (LCS) powders were introduced via a coaxial plasma torch and mixed in situ to create rapid alloy prototypes. The composition ratio for each powder component was systematically altered in nine discrete increments, increasing the ASS powder proportion from 10 to 90 (wt%) and, conversely, reducing the LCS proportion from 90 to 10 (wt%) during a single deposition pass. The weight distribution of key alloying elements in the deposited samples was analysed using Optical Emission Spectroscopy (OES) and compared to the corresponding theoretical chemical weight percentages. Furthermore, the ferrite fraction in the deposited samples was measured along the length of the deposition using a Feritscope. Light optical, scanning electron microscopy and Vickers hardness indentation measurements were performed on each of the nine samples to assess the microstructural and physical properties. The results demonstrate multi-material direct energy deposition's promising and cost-effective capabilities for rapid alloy development.