NdFeB Alloy Flakes

Ι What Are NdFeB Alloy Flakes?

NdFeB alloy flakes, referred to as thin NdFeB alloy thin sheets produced by the strip casting process, are also known as strip-cast NdFeB flakes or strip-cast Nd-Fe-B flakes. These flakes are a critical intermediate material for manufacturing sintered Neodymium magnets. The quality of the flakes significantly determines the performance of the final magnets.

Neodymium magnets are typically produced from pure metals or intermediate alloys. The raw materials are melted using medium- to low-frequency induction heating, where an alternating magnetic field generates eddy currents to heat and melt the materials in a vacuum or inert atmosphere. The molten alloy is stirred to ensure homogenization, followed by degassing and slag formation before casting. Casting is a critical step, as the phase composition, microstructure, and spatial distribution significantly affect the magnetic properties of the final magnet.

Slow cooling of NdFeB alloys inevitably forms the α-Fe phase, a soft magnetic phase at room temperature that severely degrades permanent magnet performance. Rapid cooling is essential to suppress α-Fe formation. Traditional ingot casting has evolved to reduce ingot thickness, from large cylindrical ingots (10 cm in diameter) to thinner slabs (2–4 cm). Ingot casting is cost-effective and simple, suitable for standard Neodymium magnet production, but it results in uneven grain sizes, ranging from fine rapidly cooled grains to coarse equilibrium-cooled grains, often with α-Fe precipitation. Prolonged heat treatment below the alloy’s melting point can reduce α-Fe but leads to undesirable accumulation of the Nd-rich phase, hindering optimal grain boundary phase distribution in Neodymium magnets.

To address these challenges, strip casting, developed by Showa Denko K. K., emerged as a superior method. In this process, molten alloy is poured through a tundish onto a rapidly rotating water-cooled metal wheel, forming thin NdFeB alloy flakes (0.2–0.6 mm) with fine, uniform grains and optimized Nd-rich phase distribution, ideal for high-performance magnet production.

Like Neodymium magnet blanks, NdFeB alloy flakes have become an independent product in the highly specialized NdFeB industry. They are a critical intermediate material in the supply chain, with an annual global trade volume exceeding 30,000 metric tons in recent years.