Effect of Rare Earth Elements Burning Loss on Microstructure and Properties in TbDyFe

Abstract

In order to simulate low vacuum experimental environment,Tb0.27Dy0.73Fe1.91 alloy round bars were prepared through melting with Tb, Dy and Fe elements, directional solidification and heat treatment in low vacuum environment. The magnetostriction of the alloy rods was tested. The microstructures and the causes of defects in the alloy were investigated. The results indicate that under the low vacuum experimental environment, there are plenty of twin dendritic lamellar microstructures and ordinary twin microstructures are generated in alloy, among which the mechanical properties and "jump" effect of twin dendritic lamellar structures are good, while the ordinary twins are bad to the magnetostrictive property in the alloy. REFe2 and REFe3 coupling phase is the main phase in the matrix, the burning loss of rare earth elements lead variations in chemical composition, resulting coupling growth with REFe3 phase and REFe2 phase. The thermal stress and the burning loss of rare earth elements segregate at grain boundaries resulting in the presence of micro-cracks and micro-holes. These microstructures and defects generate bad impact on mechanical properties and magnetostriction of TbDyFe alloy rods.

Keywords

• TbDyFe
• vacuum experimental environment
• defect
• magnetostriction
• twin