Effect of two-steps heat treatment on the mechanical properties and magnetostriction of 〈1 1 0〉 oriented TbDyFe giant magnetostrictive material

〈1 1 0〉 oriented rods of TbDyFe giant magnetostrictive alloy have been prepared by zone melting directional solidification method. Two steps heat treatments were performed at 1353 K for 2 h, followed by heating at 673, 773, 873, 973 K for 4 h in argon atmosphere and air cooling. The effect of a two steps heat treatment on the mechanical properties, fractography and magnetostriction of TbDyFe has been studied. It was found that the largest values of impact toughness, compression strength and magnetostriction were achieved when the alloy was heat-treated at 873 K. Room temperature Vickers indentation was performed to access the fracture toughness, and with heating temperature increasing from 673 to 973 K, the fracture toughness was gradually improved. The change of mechanical properties and magnetostriction of TbDyFe was due to a change of the relative dimensions and distribution of the rare earth-rich phase caused by the two steps heat treatment.