Amorphous grain size refinement

Figures 4(a) and 4(b) show the relationship between the average grain size and the coercivity in various Fe-based nanocrystalline soft magnetic alloys prepared by crystallization of amorphous precursors (For details, see Herzer [13], Yoshizawa [31], Muller and Mattem [32], Fujii et al. [33], and Suzuki et al. [34, 35]). As shown in Fig. 4(a), the coercivity Ha of the nanocrystalline Fe-Si-B-M-Cu (M = IVa to Via metal) alloys follows the predicted D6 dependence in a D range below LO ( 30 to 40 nm for this alloy system) although the plots deviate from the predicted D6 law in the range below H0 1 A/m where the effect of grain refinement on is overshadowed by magneto-elastic and annealing induced anisotropies. Hence, the experiments are better described by Hc [a2 + where a...

HPT has been successfully applied for microstructure refinement in metals, alloys and not long ago in composites and in semiconductors [17,18], as well as consolidation of nanopowders [7], Among new developments in HPT processing we would like to emphasize also the observation of SPD-induced nanocrystallization in initially amorphous alloys producing nanocrystalline materials with a grain size of 10-15 nm [19],... 

Laser treatment (glazing, annealing, crystal structure modification) A method of rapidly heating and cooling a surface in order to density it, refine the grain size, crystallize an amorphous material, etc. Example Laser treatment of an amorphous silicon film to convert it into a polysilicon material. 

The lumps of silieon carbide obtained on dismantling the furnace are taken to a sorting area and broken down with hydraulic equipment and compressed air hammers. The finely crystalline outer zone (the so-called amorphous zone) is further size reduced (e.g., in a jaw crusher) and is usually returned to the furnace process by adding it to the coke/sand mixture. Alternatively, this 90-95% SiC material is a valuable raw material for the produetion of grain refiners for the ferrous metal industry. 

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