Powder metallurgical processing of Tb0.27Dy0.73Fe2−X (0<X≤0.5) by a hydrogen-decrepitation (HD) route

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Abstract
The hydrogen absorption/desorption behavior of giant magnetostrictive alloys represented by the general formula Tb0.27Dy0.73Fe2−X (0<X≤0.5) has been investigated to provide background information for the production of powder by the hydrogen‐decrepitation (HD) route. X‐ray‐diffraction studies indicate a range of hydriding behaviors depending upon the particular conditions. Thus, cubic, rhombohedral, and amorphous hydrides have been observed and under certain conditions disproportionation occurs with the production of iron and rare‐earth hydrides. Metallographic examination of the latter material reveals the phases produced by this disproportionation. Sintered compacts have been made from the disproportionated material by the HD process and compacts with up to 96% of theoretical density have been achieved after only 1‐h sinters. The static magnetostrictive properties of these compacts have been investigated, and compare well with values obtained by other workers on samples produced using conventional powder metallurgical methods. The HD process appears to offer significant advantages over more conventional powder metallurgical routes for the production of compacts of these materials.