Novel mechanisms for solid-state processing and grain growth with microstructure alignment in alnico-8 based permanent magnets

Abstract

An estimated 750,000 new hybrid electric and plug-in battery vehicles, most with permanent magnet synchronous alternating current (PMAC) drive motors, took to the road in 2016 alone. Accompanied by 40% year over year growth in the EV market significant challenges exist in producing large quantities of permanent magnets (on the order of tens of millions) for reliable, low-cost traction motors [IE Agency, Energy Technology Perspectives (2017)]. Since the rare earth permanent magnet (REPM) market is essentially 100% net import reliant in the United States and has proven to have an unstable cost and supply structure in recent years, a replacement RE-free PM material must be designed or selected, fully developed, and implemented. Alnico, with its high saturation magnetization and excellent thermal stability, appears to be uniquely suited for this task. Further, while alnico typically has been considered a relatively low coercivity hard magnet, strides have been made to increase the coercivity to levels suitable for traction drive motors [W Tang, IEEE Trans. Magn., 51 (2015)]. If a simple non-cast approach for achieving near [001] easy axis grain aligned permanent magnets can be found, this would allow mass-produced final-shape anisotropic high energy product magnets suitable for usage in compact high RPM rotor designs. Therefore, a powder metallurgical approach is being explored that uses classic compression molding with “de-bind and sinter” methods, where a novel applied uniaxial loading, and an applied magnetic field may create final-shape magnets with highly textured resulting microstructures by two different mechanisms. Results indicate a positive correlation between applied uniaxial load and resulting texture (Fig. 1), along with benefits from using an applied magnetic field for improved texture, as well. The apparent mechanisms and resulting properties will be described using closed loop hysteresisgraph measurements, EBSD orientation mapping, and high-resolution SEM.

Evaluation of the Development Capability of the New Energy Vehicle Industry: An Empirical Study from China

“…In addition, a high degree of autonomous control can shorten the cycle of results conversion in the new energy sector and reduce the initial cost of discovery [24]. Studies have shown that the electric vehicle market grew by 40% year-on-year in 2018, and manufacturing is possible with core components such as traction motors that are independently developed and safe [25].…”

Manufacturing Processes for Permanent Magnets: Part I—Sintering and Casting

“…Significant effort has been devoted to developing simple non-cast approaches for achieving [001] easy axis aligned alnico magnets. [46][47][48][49][50][51] Abnormal grain growth (AGG) is detected during the compaction of the pre-alloyed gas atomized spherical powders. This leads to increased texturing control without the costly directional casting, i.e., energy product increases from 38 kJ/m 3 to 52 kJ/m 3 (4.8-6.5 MGOe) primarily because of $ 24% increase of loop squareness during the AGG process.…”

Factors Influencing the Development Ability of Intelligent Manufacturing of New Energy Vehicles Based on a Structural Equation Model

“… 11 Kassen et al proposed that the electric vehicle market would grow by 40% year-on-year in 2018. 12 Only with independent research and development, safe and reliable manufacturing to produce traction motors and other core components can have the core competitiveness of IM. 13 …”

“…Tabor believed that a high level of IM could shorten the transformation cycle of new energy vehicles and reduce initial cost . Kassen et al proposed that the electric vehicle market would grow by 40% year-on-year in 2018 . Only with independent research and development, safe and reliable manufacturing to produce traction motors and other core components can have the core competitiveness of IM …”

“…11 Kassen et al proposed that the electric vehicle market would grow by 40% year-on-year in 2018. 12 Only with independent research and development, safe and reliable manufacturing to produce traction motors and other core components can have the core competitiveness of IM. 13 Chengpeng believed that the Made in China 2025 plan had made it clear that the development strategy of China's NEVs was to vigorously develop pure electric vehicles and fuel cell vehicles.…”