ADVANCED MATERIALS & PROCESSES | MARCH 2026 6 METALS | POLYMERS | CERAMICS prevent the deposition of corrosion products, and enable clear visualization of the exact locations where pits form,” says researcher Masashi Nishimoto. The team applied their technique to ADC12 (Al-12%Si-2%Cu), a die-cast Al alloy used for automotive parts. With alloys, numerous intermetallic compounds form during solidification, creating electrochemical inhomogeneities that are thought to cause pitting corrosion. However, conventional corrosion tests in sodium chloride solutions result in widespread discoloration of intermetallic compounds and deposition of corrosion products, obscuring pit initiation sites. This makes it difficult to pinpoint the precise cause. By using a boric-borate buffer solution, the new technique suppresses alkalization on intermetallic compounds. This prevents discoloration and reduces corrosion product deposition, allowing clear observation of pit initiation and early growth. Subsequent analysis by scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy revealed that pits originate in the final solidification region. However, not all final solidification regions become a pit, which suggests that pit initiation also depends on specific local chemical compositions and microstructural features. “Being able to observe where and how these pits form is an exciting advancement, since it may help us find ways to prevent or slow down 2D TOPOLOGICAL INSULATOR DISCOVERY Physicists from University of Jyväskylä and Aalto University, both in Finland, experimentally realized a 2D topological crystalline insulator— a quantum material theoretically predicted for over a decade. Researchers created the material by growing an atomically thin, two-layer film of tin telluride on a niobium diselenide substrate. Using molecular beam epitaxy and low-temperature scanning tunneling microscopy, the team characterized the electronic properties of the system with atomic-scale precision. In this 2D system, they observed pairs of conducting edge states that are protected by the symmetry of the crystal lattice. The edge states form within a large electronic band gap exceeding 0.2 eV. Measurements show that the SnTe film experiences compressive strain from the underlying substrate, which plays a crucial role in stabilizing the topological phase. Further, results show that the topological edge states can be tuned by strain, offering a method to control their electronic properties. Firstprinciples quantum-mechanical calculations confirm the topological origin of the observed edge states. The researchers also directly probed interactions between neighboring edge states, revealing energy shifts driven by a combination of electrostatic interactions and quantum tunneling. Because of the large band gap, the topological properties are expected to remain strong up to room temperature. According to the team, these results provide a new experimental platform for studying strain-tunable 2D topological states and may enable future advances in spin-based electronics and nanoscale devices. www.jyu.fi. PINPOINTING PITTING CORROSION IN ALUMINUM Scientists at Tohoku University, Japan, developed a technique to identify the initiation sites of pitting corrosion, which occurs when aluminum alloys are exposed to sodium chloride solutions. The discovery could accelerate development of Al alloys with improved corrosion resistance. “This innovative study combines realtime optical microscopy with a boric-borate buffer solution, in order to suppress discoloration around intermetallic compounds, This artistic AI illustration represents the team’s 2D system. Courtesy of University of Jyväskylä. Cross-sectional scanning transmission electron microscopy image of a pit initiation site identified using the developed technique. Courtesy of Kaito Takeuchi, Masashi Nishimoto, and Izumi Muto. A multi-institution research team led by the University of California, Los Angeles, discovered a metallic material with the highest thermal conductivity ever measured among metals. The team reported that metallic theta-phase tantalum nitride conducts heat nearly three times more efficiently than copper or silver. ucla.edu. BRIEF
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