High coercivity, anisotropic, heavy rare earth-free Nd-Fe-B by Flash Spark Plasma Sintering

The Evolving Use of Magnets in Surgery: Biomedical Considerations and a Review of Their Current Applications

The novel use of magnetic force to optimize modern surgical techniques originated in the 1970s. Since then, magnets have been utilized as an adjunct or alternative to a wide array of existing surgical procedures, ranging from gastrointestinal to vascular surgery. As the use of magnets in surgery continues to grow, the body of knowledge on magnetic surgical devices from preclinical development to clinical implementation has expanded significantly; however, the current magnetic surgical devices can be organized based on their core function: serving as a guidance system, creating a new connection, recreating a physiologic function, or utilization of an internal–external paired magnet system. The purpose of this article is to discuss the biomedical considerations during magnetic device development and review the current surgical applications of magnetic devices.

Critical Minerals for Zero-Emission Transportation

Fundamentals of critical minerals and their paramount role in the successful deployment of clean energy technologies in future transportation are assessed along with current global efforts to satisfy the needs of automotive supply chains and environmental concerns. An implementation of large quantities of minerals, in particular metals, into the manufacturing of strategic components of zero-emission vehicles will bring new challenges to energy security. As a result, a reduced dependency on conventional hydrocarbon resources may lead to new and unexpected interdependencies, including dependencies on raw materials. It is concluded that to minimize the impact of a metal-intensive transition to clean transportation, in addition to overcoming challenges with minerals mining and processing, further progress in understanding the properties of critical materials will be required to better correlate them with intended applications, to identify potential substitutions and to optimize their use through the sustainable exploration of their resources and a circular economy.

Strong texture in nanograin bulk Nd-Fe-B magnets via slow plastic deformation at low temperatures

Nanograin magnets are potential candidates for ultrastrong magnets with high coercivity and high energy product. However, existing nanograin bulk magnets exhibit modest energy products because desired structures with nanoscale grain size and strong orientation (texture) are often difficult to obtain. This study describes a synchrony of the nanoscale grain size and strong texture in bulk Nd-Fe-B magnets by plastic deformation with slow strain rates at temperatures well below the melting point of the Nd-rich phase. High grain orientation (>90%) has been achieved for nanoscale grain sizes of 80-110 nm, giving the nanograin bulk magnets record high energy products (≥45 MGOe). Loosely-packed thick grain boundaries and creep-like stress-strain curves have been observed. Grain boundary mediated creep-like deformation is proposed as the mechanism for the high-degree nanoscale grain alignment under the deformation conditions without liquid phase. The effect of the strain rate on the texture and magnetic properties has been investigated systematically.

On the Process and Product Fingerprints for Electro Sinter Forging (ESF)

Electro sinter forging (ESF) represents an innovative manufacturing process dealing with high electrical currents. Classified in the category of electrical current assisted sintering (ECAS) processes, the main principle is that Joule heating is generated inside the compacted powder, while the electrical current is flowing. The process is optimized through the analysis of the main process parameters, namely the electrical current density, sintering time, and compaction pressure, which are also evaluated as process fingerprints. The analysis was conducted on commercially pure titanium powder. Small discs and rings were manufactured for testing. The influence of the process parameters was analysed in terms of the final material properties. The relative density, microstructures, hardness, and tensile and compressive strengths were analysed concerning their validity as product fingerprints. Microstructural analyses revealed whether the samples were sintered or if melting had occurred. Mechanical properties were correlated to the process parameters depending on the material. The different sample shapes showed similar trends in terms of the density and microstructures as a function of the process parameters.