Hyperfine fields and magnetoelastic surface effects in Fe72Cu1.5Nb4Si13.5B9 nanocrystalline alloy

In this work hyperfine fields of two-phase nanocrystalline Fe72Cu1.5Nb4Si13.5B9 alloys were studied in order to verify the existence of surface effects. To obtain a series of nanocrystalline samples with small grains of different sizes, a special non- -isothermal annealing procedure of an initially amorphous ribbon was applied. In the case of samples with a significant amount of crystallites, a high field (about 27.5 T) component of continuous part of the hyperfine field distribution was found that could be attributed to boundary regions between the grains and rest of the sample. The existence of the surface effects was confirmed in the magnetostrictive experimen

Structure and magnetic properties of Fe–Nb–B amorphous/nanocrystalline alloys produced by compaction of mechanically alloyed powders

Mechanical alloying of Fe75Nb10B15 and Fe85Nb5B10 systems has been performed from an initial mixture of elemental powders. A bcc supersaturated solid solution is developed during milling for both alloys. However, Fe75Nb10B15 alloy also develops an amorphous phase, which amount increases with milling time. Milled powder samples were compacted at 7.7 GPa at different temperatures. Scanning electron microscopy images show that the presence of amorphous phase enhances the quality of compaction. Compaction at 823 K preserves both microstructure and magnetic properties of as-milled powders in both alloys. Compaction at 973 K affects mainly the crystalline fraction of the alloy with 10 at. % Nb. Compaction at 1273 K yields the formation of bcc Nb and fcc Fe23B6 phases, which magnetically harden the material

Correlation between microstructure and temperature dependence of magnetic properties in Fe 60 Co 18 ( Nb , Zr ) 6 B 15 Cu 1 alloy series

Temperature dependence of magnetic properties of nanocrystalline Fe60Co18Cu1B15Nb6−xZrx (x =0, 3, 6) alloys has been studied at different stages of devitrification. Transmission electron microscopy shows nanocrystals of the size �5 nm, which remains almost constant along the nanocrystallization process. Curie temperature of the residual amorphous phase decreases as nanocrystallization progresses for all the studied alloys. Thermal dependence of the exchange stiffness constant is obtained from the measurement of specific magnetization and coercivity as a function of crystalline fraction and temperature for the three studied alloys

Phase transformation in Al3Ni2 alloy during mechanical alloying and heating of milling products

score: 15collation: 272-27

Nanocrystallization and Magnetic Properties

score: 0collation: 507-51

Influence of Sn Addition on the Amorphization and Thermal Stability of CuTiZrNi Powders Processed by Mechanical Alloying

score: 0collation: 917-92

Magnetically soft nanocrystalline powders of Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 obtained by mechanical alloying and ball milling

abstractEN: <p> Magnetically soft nanocrystalline powders of Finemet alloy (Fe _73.5 Cu ₁ Nb ₃ Si _13.5 B ₉ ) were produced applying three techniques: (i) mechanical alloying of elemental powder mixtures, (ii) ball milling of crystalline ingots produced by induction melting of constituent elements of the alloy and (iii) ball milling of partially nanocrystalline ribbons (obtained initially as amorphous and nanocrystallized by annealing at 550°C for 1 h). Strong influence of powder manufacture method and milling time on magnetic softness was observed. Ball milled nanocrystalline ribbon exhibited the lowest coercive field H _c , while mechanically alloyed elemental powders - the highest one. In all cases H _c increased with processing time. The observed magnetic hardening of very soft nanocrystalline Finemet ribbon with the milling time was due to the decreasing size of the powder particles. </p>score: 0collation: 659-66