STRUCTURAL STUDIES OF SOME HYDROGEN-TREATED MATERIALS RELATED TO THE HDDR-PROCESS OF ND2FE14B-BASED ALLOYS

Hydrogen-treated Nd14.0Fe66.9Co11.0Ga1.0Zr0.1B7.0 alloys have been exa mined by means of powder X-ray diffraction(XRD) and electron probe mic roanalysis(EPMA) to understand the mechanism of the development of mag netic anisotropy in the hydrogenation, decomposition, desorption, and recombination(HDDR) process of Nd2Fe14B-based alloys. It has been reve aled that Nd2Fe14B phase can coexist in equilibrium with decomposed pr oducts, namely, alpha-Fe, NdH2, and Fe2B, in the presence of hydrogen of an atmospheric pressure over the temperature ranging 1113 to 1153 K . It was observed that Co and Ga condensed into a Nd2Fe14B phase durin g hydrogen-treatments, resulting in a thermodynamically stable Nd-2(Fe ,Co,Ga)(14)B compound. Well-developed anisotropic materials were obtai ned via the HDDR-process when the hydrogen-treatment was accomplished under such conditions that Nd-2(Fe,Co,Ga)(14)B coexists with the decom posed products. All our results give a favorable support to the previo us proposal that the crystallographic orientation of the original allo y can be conveyed via the undecomposed Nd2Fe14B particles throughout H DDR processing.