Material and process design for additive manufacturing of hard metals

点击翻译按钮获取中文摘要

The design of materials resistant to wear is an area that could offer significant industrial benefits ranging from applications in the construction, machining and manufacturing sectors. Despite that, wear resistant material innovation, in particular related to metal-based materials, is limited by constraints encountered in processing and prototyping and hence, few novel materials have been able to compete with tungsten carbide (WC) based components. However, the rapid growth and development of additive manufacturing (AM) methods offers an avenue for the holistic design of both new wear resistant materials and their manufacturing process. Using AM, processing can be modified to occur at non-equilibrium states and these methods can be used to tailor the formation of hardening phases to a later stage in the post-processing cycles, hence allowing for improved material processability. It is therefore the aim of this project to investigate avenues for materials design and processing for wear resistant applications using AM-based methods. The project will focus on the evaluating the potential and processability of three classes of materials initially: high entropy alloys and high entropy carbides and the possibilities of high entropy cemented carbide design and high-hardness steels. Material design efforts will focus on high entropy alloys and hardenable steels. High entropy alloys have provided a domain of metallurgical research that has expanded exponentially over the last few years, yet few studies have evaluated high entropy alloys for wear resistance. In this work several compositions of refractory metal high entropy alloys (HEAs) will be initially evaluated for hardness and processability, before further AM processing and wear resistance tests can be carried out. In addition, the possibilities of inducing significant carbide formation using post-AM processing heat treatments will be explored. Several HEAs are known to result in the precipitation of carbide species following prolonged exposures at high temperatures. By experimenting with the C content as well as AM processing within promising systems, the kinetics of carbide formation can be significantly altered to induce carbide formation with industrially viable heat treatment durations. Furthermore, and if time permits, several species of high-hardness high entropy carbides (HEC) based on refractory metals are known to exist and HEC-HEA type cemented carbide systems may also be evaluated.