Structure and magnetic properties of (Nd, Pr)-Fe-B-Ti alloys prepared by mechanical alloying

With the purpose of finding promising nanostructured hard magnetic material s, the structure and magnetic properties of PrxFey2-xB8, Pr10Fe82-y,TiryB8, and Pr10-DNdDFe76B8-zTi6+z alloys prepared by mechanical alloying and subs equent annealing have been studied. The best values of 4 pi M-r = 0.8 kGs, H-i(c) = 18.8 kOe and (BH)(max) = 13.9 MGOe, are obtained for the series of PrxFe92-xB8 With x = 16, which are similar to the results reported previou sly for the Nd-containing counterpart. It has been found that the ratio M-r /M-s notably decreases with increasing mean grain size of the sample with x = 10, whereas the coercivity increases slightly. Far the series of Pr10Fe8 2-yTiyB8 and Pr10Fe76B8-zTi6+z, when O less than or equal to y less than or equal to 2, the Pr2Fe14B phase can be formed, accompanied by some alpha-(F e, Ti), a trace of Pr2O3 and Pr-rich phases similar to Nd-rich phases in th e Nd-Fe-Ti-B alloys. When y greater than or equal to 4, besides the phases mentioned above, the Pr(Fe, Ti)(7) phase with the TbCu7 structure is also o bserved. When z greater than or equal to 2, with increasing Ti content, the Curie temperature of the Pr(Fe, Ti)(7) phase increases, while the Curie te mperature of Pr2Fe14B decreases and the magnetic properties of the series d egrade. In the series of Pr10-DNdDFe76B4Ti10 it is found that the substitut ion of Nd for Pr leads to a gradual disappearance of the 1:7 phase with the TbCu7 structure. A nearly single phase Nd2Fe14B is formed for D greater th an or equal to 8. The coercivity of the samples is drastically enhanced by Nd substitution.