The Application of the Rare Earths to Magnesium and Titanium Metallurgy in Australia

Abstract

These elements have huge relevance in the modern world, in applications spanning electronics, biomedicine, structural materials, and more; many rely on their unique electronic properties as the only nonradioactive elements with electrons occupying the f-subshell. [1] However, REEs have long been topics of moderate interest for their application in metallurgy, such as the bulk purification of steels and other alloys, or the improvement of the hightemperature properties of Mg alloys. [3] In recent years, however, progress in materials science has intensified interest in the REE elements. Notably, these are the rise of magnesium (Mg)-based alloys for both biodegradable implant materials and highly weight-sensitive applications in the automotive and aerospace sectors, and the growth of powder-metallurgy (PM) and additive-manufacturing (AM) fabrication methods for titanium (Ti). This change can be seen graphically in Figure 1, with the sharp spike in publications starting shortly after the new millennium. Thus, the importance of REEs, particularly the L-REEs, is highlighted in both the biomedical sector and in high-performance aerospace and automotive roles. Given the biomedical sector represented some 62 000 jobs and $4.9 billion of value to the national GDP in 2016, [5] Australia is well positioned to benefit from advances in biomedical technology; the recent launch of the Australian Space Agency suggests that the aerospace sector may soon grow as well. [6] As such, here, we will attempt to summarize relevant research over the past decade in this field, highlighting work from Australian institutions; the aim of this summary is to help assist in both understanding the current state-of-the-art, and to identify promising areas for future research where Australia is well positioned to leverage existing expertise. Rare Earth Application to Magnesium AlloysMuch of the current research on REE-containing alloys is concerned with Mg alloy systems. Mg-based alloys have long been attractive options in aerospace and automotive applications; at ≈1.7-8 g cm −3 , Mg-based alloys have the lowest density of the common structural metals by a substantial margin, [7] yielding exceptional specific strengths/stiffnesses ideal for weightsensitive applications. Beyond aerospace and automotive sectors, however, the last two decades have seen the sharp rise in interest by the biomedical sector. In this regard, Mg and its alloys are again well suited; Mg shows exceedingly low toxicities coupled with numerous bioactive effects, and can achieve Rare earth elements (REEs) have found application in metallurgical processes for nearly a century due to their unique chemical and physical properties but have gained increased attention in recent decades. Notably, the use of these elements may assist in the development of advanced magnesium and titanium products for applications spanning biomedicine, aerospace, and the automotive industry. To this end, current progress in this area, highlighting work done in Australian research organizations with partic...

Sustainability applications of rare earths from metallurgy, magnetism, catalysis, luminescence to future electrochemical pseudocapacitance energy storage

“…41 The vast majority of research on rare earth alloys focuses on lightweight magnesium (Mg) alloys, which are widely employed in high-performance automobiles and the aerospace industry. 42 Mg-based alloys are suited for application in gravity-sensitive devices due to Mg's low density of 1.7 g cm −3 , which is the lowest among typical structural metals. However, their poor ductility and susceptibility to corrosion in liquid environments restrict their widespread utilization.…”

Environmental Technologies to Treat Rare Earth Element Pollution: Principles and Engineering

“…REE are used in the preparation of Mg-alloys or titanium-alloys due to their high solid-solubility, structural integrity, and corrosion resistance (by scavenging undesirable contaminants and stabilizing the oxide/hydroxide surface)an ideal property in weight-sensitive and biomedical applications (Biesiekierski et al, 2020;Willbold et al, 2015). The Pt-REE alloy has been adopted as an active and durable electrocatalyst as its negative alloying energy or enthalpy of formation confers resistance against dissolution .…”

Enhanced Electromagnetic Wave Absorption for Y2O3-Doped SiBCN Ceramics

“…Because of the existence of an empty d orbital, the rare-earth metal could regulate the electronic band structure and lattice constant of materials to control the optical, electrical, and magnetic properties of materials. − For example, Yu et al found that the 4d orbital of Y affected the dispersion bandwidth of CdO because of its antibonding expansion mechanism, the optical bandwidth of Y–CdO was increased from 2.86 to 3.27 eV, and the visible-light transmittance was greater than 80%. Torayev et al further revealed that Y distorted the lattice of BaZrO 3 and increased the atomic spacing between Y–O and Zr–O, so the proton diffusion activation energy was increased from 24.1 to 45.0 kJ/mol and inhibited the proton transport between ZrO 6 octahedrons.…”