Metal alloys based on the copper-zinc system, commonly known as brasses, are arguably the most versatile and widely utilized families of materials. Brass applications range from everyday household items to apparel components, plumbing fixtures, electronic hardware, military munitions, and currency coins. Leaded “free-machining” brasses have long been a key industry-enabling material due to their excellent machinability, workability and toughness, coupled with low sliding friction and corrosion nobility.
However, the brass industry is on the cusp of dramatic change. The maximum amount of lead permitted in "lead-free” brass was reduced in California from 4% to 0.25% in 2010, and the US federal government moved to this same low limit from 8% in the Reduction of Lead in Drinking Water Act in 2014, with compliance certification required in the near future. The hurdles for compliance with this regulation are immense, with thousands of US communities subject to significantly higher lead levels than the much-publicized case of Flint, Michigan. In Australia, 56% of sampled household water samples have detectable levels of lead, with 8% exceeding drinking water guidelines, and legislation is expected that will dramatically reduce the allowable lead in brass plumbing from the current 4.5%. Such landmark restrictions have placed brasses in the metallurgical spotlight with a pressing need to meet new health and industrial processing demands.
In 2021, Prof Bassman and Prof. Aurora Pribram-Jones (HMC Chemistry '09) at UC Merced were awarded a grant from the International Research Experiences program at NSF: "US-Australia collaboration on a new class of lead-free copper alloys to meet international health demands" (awards 2106617 to HMC and 2106756 to UC Merced). This is Prof. Bassman's fourth NSF grant to support collaboration with researchers at UNSW and it is exciting that our long-time collaborator is now a co-PI and students from UC Merced will join the team. We will soon be recruiting the cohort who will start learning in January and travel to Australia in summer 2024!
In 2013-2015 HMC students developed a family of compositionally-complex brass and bronze alloys at UNSW - this was one of our first projects in the field. Students and collaborators
This work led to further work at UNSW and spawned several projects, including our effort to and commercialize lead-free brass alloys that are based on the earlier work with Cu-Ni-Mn-(Al and.or Zn). Australian collaborators and Prof Bassman founded Advanced Alloy Holdings to connect with worldwide metal alloy producers to form collaborations for development toward commercialization of brass alloys and others that we have been developing. We intend for our work to go beyond academic results and become real world alloys!
Although we weren't able to have a full group travel to Australia to work on this project in 2022, students began thermodynamic modeling and computational work that already won a Best Poster prize in this MRS conference symposium in May 2022.
In 2023 two HMC students and two UC Merced students traveled to UNSW. The experimental students developed a new alloy that our industry partners find very promising! The computational students have made good progress on methods to predict ductility as a function of composition.
Laspa Fellows for early brass work: Cody Crosby '15 (engineering), Aarthi Sridhar '15 (engineering), Mo Zhao '16 (engineering), Shifrah Aron-Dine '16 (physics), and so far for the new lead-free brass project: Kaitlyn Paulsen '22 (engineering), Anna Soper '22 (physics/math), Emma Zhang '24 (physics/math), Carmen Horenstein '24 (engineering), Carleton Imbens '25, Lucien Tsai '24 (physics). Many more to come!