Influence of solidification speed on the structure and magnetic properties of Nd10Fe81Zr1B6 in the as-cast state

Abstract

The paper presents results of the structure and magnetic properties of the Nd10-xTbxFe81Zr1B6 (x = 0, 2) alloy in the as-cast state. The samples were produced using the melt-spinning method. The solidification speed was controlled indirectly by changing the linear velocity of a copper drum. Based on magnetic and structural studies, it was found that samples obtained while the linear velocity of the copper drum was equal to 20 m/s had good hard-magnetic properties. The substitution of 2 % of Nd by Tb led to grain growth of both the a-Fe (9 nm and 24 nm for x = 0 and x = 2) and Nd2Fe14B phases (41 nm and 70 nm for x = 0 and x = 2, respectively). The grain growth to sizes higher than the exchange interaction distance in the sample with Tb resulted in a bimodal shape of the demagnetization curve. The samples obtained at higher linear speeds of the copper drum were composed of amorphous matrices with small amounts of crystalline phases and had weak, soft-magnetic properties. Keywords: permanent magnets, nanocomposities, X-ray diffraction, exchange interactionŝ lanek predstavlja rezultate {tudije strukturnih in magnetnih lastnosti zlitine Nd10-xTbxFe81Zr1B6 (x = 0, 2) v litem stanju. Vzorci so bili pripravljeni z ulivanjem na hitro vrte~em se valju. Hitrost strjevanja je bila posredno kontrolirana s spreminjanjem linearne hitrosti bakrenega valja. Magnetne in strukturne {tudije so pokazale, da imajo vzorci, dobljeni pri linearni hitrosti bakrenega valja 20 m/s, dobre trdomagnetne lastnosti. Nadomestilo z 2 % atomskega dele`a Nd s Tb, je povzro~ilo rast zrn obeh faz a-Fe (9 nm in 24 nm pri x = 0 in x = 2) in Nd2Fe14B (41 nm in 70 nm pri x = 0 in x = 2). Rast zrn, do velikosti, ve~je od izmenjalne interakcijske razdalje v vzorcu s Tb, se je pokazala v bimodalni obliki demagnetizacijske krivulje. Vzorci, dobljeni pri ve~jih linearnih hitrostih bakrenega valja, so bili sestavljeni iz amorfne osnove z majhnim dele`em kristalnih faz in so imeli slabe mehko magnetne lastnosti. Klju~ne besede: permanentni magneti, nanokompoziti, rentgenska difrakcija, izmenjalne interakcije