Inventor of the Nd-Fe-B permanent magnet wins Queen Elizabeth Prize for Engineering

Permanent magnet technologies have been progressively developed since the 18th Century, but it was in the late 1960s that a step change was achieved through the invention of high-performance cobalt-based rare-earth magnets (samarium-cobalt). However, their high cost and limited natural resources restricted them to niche applications.

Dr Sagawa pioneered the development of the sintered neodymium-iron-boron (Nd-Fe-B) permanent magnet. Sagawa’s breakthrough innovation was the creation of a new compound formed by replacing the scarce and expensive cobalt and samarium with more abundant and cheaper iron and neodymium, and at the same time introducing boron to improve the magnetic properties – the first step in delivering high performance to a mass market.

Dr Sagawa then led research and development in the 1980s and early 1990s to successfully overcome the issues of sudden reduction of magnetic coercivity at high temperature, most notably by adding dysprosium to improve heat resistance.

This resulted in the development of high-volume manufacturing techniques which successfully commercialized his innovation. For even wider applications, he continued further successful development of novel techniques for reducing the amount of dysprosium or even eliminating its use.

The result was a new magnet for the mass market that almost doubled the performance of the previous best and successfully turned Nd-Fe-B magnets into a viable industrial material with wide applications. The new magnet has a significant advantage in high-efficiency and high-torque density applications, such as motors and generators for electric vehicles and wind power generation, and in more general applications where small powerful magnets are required, including robots, automation systems and domestic appliances.

Dr Sagawa was announced as the winner of the 2022 prize by Lord Browne of Madingley, Chairman of the Queen Elizabeth Prize for Engineering Foundation.