Executive Summary : | The proposed project will build on recent research in the PI's lab on developing scalable mechanical processes for the production of metal powders, specifically for AM applications. Two such processes will be investigated---abrasion-based powder production and vibration or modulation assisted machining. These methods will be employed for studying powder production with a commercially important material system---Ni-base superalloy Inconel 718---and their performance for DED-based metal AM will be benchmarked. Attendant energetics calculations will also be undertaken to make a case for scalability and energy efficiency. The market for metal powders is experiencing extraordinary growth driven by applications as diverse as additive manufacturing (AM), repair and re-manufacturing (RM), powder metallurgy (PM) and composites processing. In fact, powder applications for AM processes such as direct energy deposition and powder bed fusion alone have seen exponential growth in the last five years. Spray and deposition-based RM processes, and surface treatments, represent other emerging growth areas where there is critical need for metal powders, especially powder particulate produced from certified material, e.g., bulk alloys with specific compositions and mechanical properties (e.g., Inconel 625, Inconel 718, Ti6Al4V, stainless steel). Industry reports estimate current demand for powders at US\$4.8 billion, with an estimated growth of nearly 40\% by 2029. The particulate market in the coming years is expected to be dominated by aluminum, nickel, copper, titanium and steel alloys; as well as specialty alloys such as refractories. Current production systems for metal powders are all structured mainly around atomization processes (e.g., gas, water and plasma based), and to a smaller extent around specialized routes like ball milling, chemical processing and metal hydride-dehydride processes. The latter two are suitable mainly for specialized powder applications like the titanium system. The atomization processes are quite attractive in terms of production rates and capability to produce spherical particulate. However, this processing requires massive centralized infrastructure and large energy costs, while offering only low particle yields (typically 10-15\%). Further, atomization-based processes are inherently restrictive---they cannot be easily adapted for multiple material systems---that only adds to the cost of the final powders. These attributes are also typical of the specialized routes like milling and hydride-dehydride processes, because of their complex multi-stage processing. As a result, powder costs are quite prohibitive, with specialized Ti powders not uncommonly being priced at over 30-50$\times$ the price of cast samples of equivalent weight. The project, if successful, will represent the first major step towards adoption of scalable alternative routes for the production of metal powders for additive manufacturing applications. |