Aluminothermic reduction of CeO2: mechanism of an economical route to aluminum-cerium alloys.

Cerium oxide is a low-value byproduct of rare-earth mining yet constitutes the largest fraction of the rare earth elements. The reduction of cerium oxide by liquid aluminum is proposed as an energy- and cost-efficient route to produce high-strength Al-Ce alloys. This work investigated the mechanism of a multi-step reduction reaction to facilitate the industrial adaptation of the process. Differential scanning calorimetry in combination with time-resolved synchrotron diffraction data uncovered the rate-limiting reaction step as the origin of the reported temperature dependence of reduction efficiency. This is the first in situ study of a metallothermic reaction mechanism and will serve as guidance for cost- and energy efficient industrial process control.

How Cerium and Lanthanum as Coproducts Promote Stable Rare Earth Production and New Alloys.

The largest outputs of rare earth mining are the low-value byproducts cerium and lanthanum, which burden rare earth supply chains because they must be separated from more desirable rare earths used in magnet production. Promoting demand for cerium and lanthanum can potentially diversify the economics of rare earth mining and improve supply chain stability for all rare earth elements. A promising avenue for increasing byproduct rare earth element demand is their use in aluminum alloys; an application for cerium and lanthanum offering multiple benefits to manufacturing such as energy reduction and improved throughput. Experimental materials science and economic implications of Al-rare earth element alloys will be discussed. We show that Al-La/Ce alloys have elevated mechanical strength compared to more traditional aluminum alloys, in some formulations can be used without heat treatment, and possess a highly castable eutectic microstructure. This report presents the use of cerium and lanthanum in aluminum alloys as an example of how supply chain focused approaches to technological development can benefit stakeholders at every step in production.

Mechanical and degradation property improvement in a biocompatible Mg-Ca-Sr alloy by thermomechanical processing.

Magnesium-based alloys have attracted interest as a potential material to comprise biomedical implants that are simultaneously high-strength and temporary, able to provide stabilization before degrading safely and able to be excreted by the human body. Many alloy systems have been evaluated, but this work reports on improved properties through hot extrusion of one promising alloy: Mg-1.0 wt% Ca-0.5 wt%Sr. This alloy has previously demonstrated promising toxicity and degradation properties in the as-cast and rolled conditions. In the current study extrusion causes a dramatic improvement in the mechanical properties in tension and compression, as well as a low in vitro degradation rate. Microstructure (texture, second phase distribution, and grain size), bulk mechanical properties, flow behavior, degradation in simulated body fluid, and effect on osteoblast cyctotoxicity are evaluated and correlated to extrusion temperature. Maximum yield strength of 300 MPa (above that of annealed 316 stainless steel) with 10% elongation is observed, making this alloy competitive with existing implant materials.