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Rare-earth metal prices have fluctuated wildly

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The magnets are crucial to an enormous number of products in the automobile, electronics, power-generation, and clean-energy industries. But worldwide, it has been difficult to secure the supply of neodymium, dysprosium, and other rare-earth metals in these powerful magnets, which are stronger yet much smaller than those made with other materials. Recently rare-earth metal prices have fluctuated wildly.

In 2010, many publications, including this one, reported on China’s global monopoly on production of rare-earth metals and oxides and the country’s plans to drastically cut exports. The news caused demand for and prices of these materials, especially of dysprosium, one of the scarcest rare-earth metals, to soar. But then other market factors caused prices to fall sharply.

Rather than hunting for completely novel building blocks from which to construct new magnets free of rare-earth metals, many scientists are looking for methods to control the building blocks of known magnetic substances on a finer scale. The strategy could lead to more magnetism from less material. A handful of those researchers gathered at the recent Materials Research Society meeting in Boston to share their latest findings. They and other scientists are working to understand nanoscale magnetic phenomena and to use that information to develop a bottom-up approach to magnet-making. Other researchers are responding to the challenge by exploring methods for extracting the valuable metals from already-used commercial products, allowing them to make recycled rare-earth magnets.

Neodymium In Hydrogen Atmosphere Neodymium iron boron(NdFeB)

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Neodymium In Hydrogen Atmosphere Neodymium iron boron(NdFeB) do not perform well in the atmosphere dominated by hydrogen. It is advised to use Neodymium magnets (NdFeB )where the atmosphere has been purged with Hydrogen for many reasons, such as purity. If NdFeB magnet is used in such atmosphere special care needs to be taken.

There are two mechanisms that cause failure due to hydrogenation of the NdFeB magnet. A Neodymium Iron Boron magnet has two phases in which the Nd2Fe14B phase is the predominant phase. This is the basic molecular lattice structure of the magnet. The penetration of hydrogen molecule in the basic molecular structure causes a mechanical stress inside the molecule. The expansion of molecules results in internal breakage.

Secondly the hydrogen is absorbed by the neodymium- rich phase at the boundary. The combination of hydrogen and neodymium results in the powdery materials. This leads to the failure of the process and visually appears as if the magnet is simply crumbling away.

The isolation of magnets from the atmosphere of hydrogen is rather difficult. Many processes like coating and plating have been tested but with little success. Once the hydrogenation process begins, the rate of disintegration increases exponentially. As mechanical breakdown is introduced, the actual surface area continues to increase, thereby causing a chain-reaction effect.

However the prevention of the magnet can be easily effected by hermetically sealing the magnet. Here, a thin boundary wall is placed around the magnet which isolates the magnet from the hydrogen atmosphere entirely. The walls are either laser welded or electron-beam welded. Laser welding is preferred to weld the magnet in the magnetized condition.

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