Method of forming magnetostrictive rods from rare earth-iron alloys

Claim 1

In the manufacturing of rods of magnetostrictive alloys of iron with rare earth metals, said alloys including terbium (Tb) together with dysprosium (Dy) and/or holmium (Ho), the method steps comprising: (a) forming a molten flowable body of said rare earth-iron alloy in a crucible enclosed within a chamber, the upper surface of said molten body being in contact with an inert gas within said chamber; (b) providing an upwardly-extending hollow mold tube of refractory material positioned with its lower end portion within said molten body, the interior of said mold tube being separated from the gas in said chamber by said molten body; (c) creating a pressure differential between said chamber gas and the interior of said mold tube forcing a portion of the molten alloy to rise in said mold tube to a selected level for forming a rod; and (d) maintaining a portion of said molten alloy in said crucible extending to a level above the lower end of said mold tube, solid particles of higher melting impurities present in said alloy collecting at the surface of said molten body and remaining within said crucible as said rod is formed in said mold tube.

Claim 6

The method of manufacturing rods of grain-oriented magnetostrictive alloys, said alloys including terbium (Tb) together with dysprosium (Dy) and/or holmium (Ho), the method steps comprising: (a) forming a molten flowable body of said rare earth-iron alloy in a crucible enclosed within a chamber, the upper surface of said molten body being in contact with an inert gas within said chamber; (b) providing an upwardly-extending hollow mold tube of refractory material positioned with its lower end portion within said molten body, the interior of said mold tube being separated from the gas in said chamber by said molten body; (c) creating a pressure differential between said chamber gas and the interior of said mold tube forcing a portion of the molten alloy to rise in said mold tube to a selected level for forming a rod; (d) maintaining a portion of said molten alloy in said crucible extending to a level above the lower end of said mold tube, solid particles of higher melting impurities present in said alloy collecting at the surface of said molten body and remaining within said crucible as said rod is formed in said mold tube; (e) solidifying the rod within said mold tube and then removing it therefrom; and (f) subjecting the formed rod to free standing progressive zone melting to produce an axial grain orientation, the rod being aligned vertically with its sides unsupported and the melt zone moving upwardly along said rod.

Claim 7

The method of manufacturing rods of grain-oriented magnetostrictive alloys, said alloys including terbium (Tb) together with dysprosium (Dy) and/or holmium (Ho), the method steps comprising: (a) forming a molten flowable body of said rare earth-iron alloy in a crucible enclosed within a chamber, the upper surface of said molten body being in contact with an inert gas within said chamber; (b) providing an upwardly-extending hollow mold tube of refractory material positioned with its lower end portion within said molten body, the interior of said mold tube being separated from the gas in said chamber by said molten body; (c) creating a pressure differential between said chamber gas and the interior of said mold tube forcing a portion of the molten alloy to rise in said mold tube to a selected level for forming a rod; (d) maintaining a portion of said molten alloy in said crucible extending to a level above the lower end of said mold tube, solid particles of higher melting impurities present in said alloy collecting at the surface of said molten body and remaining within said crucible as said rod is formed in said mold tube; (e) solidifying the rod within said mold tube and then removing it therefrom; and (f) subjecting the formed rod to free standing progressive zone melting to produce an axial grain orientation, the rod being aligned vertically with its sides unsupported and the melt zone moving upwardly along said rod.