Composites with large magnetostriction

A method of making a magnetostrictive composite comprising:

• mixing an epoxy resin, fumed silica, a flexibilizing agent and a cycloaliphatic amine curing agent to form a resin mixture, wherein the flexibilizing agent is a flexible diepoxide of EEW 390-470 or a mixture of a high molecular weight polyamine of MW 2000-5000 and a low molecular weight polyamine of MW 230-450;
• mixing 2-50 vol. % magnetostrictive particles into the resin mixture to form a composite paste;
• and
• curing the composite paste in the presence of a magnetic field whereby the magnetostrictive particles align in the direction of the field during curing.

A method of making a magnetostrictive composite comprising:

• mixing a bisphenol-A diepoxide resin, fumed silica, a cycloaliphatic amine curing agent, a high molecular weight polypropyleneoxide diamine or triamine of MW 2000-5000, a low molecular weight polypropyleneoxide diamine or triamine of MW 230-450 and a tertiary amine accelerator to form a resin mixture;
• mixing 8-50 vol. % magnetostrictive particles comprising an alloy of iron, terbium and dysprosium into the resin mixture to form a composite paste;
• and
• curing the composite paste in the presence of a magnetic field whereby the magnetostrictive particles align in the direction of the field during curing.

A magnetostrictive composite comprising:

• 50-92 vol. % resin matrix resulting from curing a composite paste comprising a cured form of a bisphenol-A diepoxide resin, fumed silica, a cycloaliphatic amine curing agent, a high molecular weight polypropyleneoxide diamine or triamine of MW 2000-5000, a low molecular weight polypropyleneoxide diamine or triamine of MW 230-450 and a tertiary amine accelerator;
• and
• 8-50 vol. % magnetostrictive particles comprising an alloy of iron, terbium and dysprosium dispersed throughout the resin matrix and oriented in the direction of their magnetic easy axes,
• wherein the composite exhibits a magnetostrictive coefficient of at least 500 ppm under an applied field of at least 5 kOe.