Formation of L1₀-FeNi hard magnetic material from FeNi-based amorphous alloys

【摘要】 L1₀-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe₄₂Ni_41.3Si₈ B₄ P₄ Cu_0.7 amorphous alloy,and the L1₀-FeNi formation mechanism has been studied.It is found the L1₀-FeNi in annealed samples at 400 ℃ mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 60 0 C lower than the measured onset temperature of the second stage with a5 0 C/min heating rate.Annealing at 400 0 C after fully crystallization still caused a slight increase of coercivity,which was probably contributed by the limited transformation from other high temperature crystalline phases towards L1₀ phase,or the removal of B from L1₀ lattice and improvement of the ordering quality of L1₀ phase due to the reduced temperature from520 ℃ to 400 ℃.The first stage of crystallization has hardly direct contribution to L1₀-FeNi formation.Ab initio simulations show that the addition of Si or Co in L1₀-FeNi has the effect of enhancing the thermal stability of L1₀ phase without seriously deteriorating its magnetic hardness.The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects.The approaches of synthesizing L1₀-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.更多还原

【Abstract】 L1₀-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe₄₂Ni_41.3Si₈ B₄ P₄ Cu_0.7 amorphous alloy,and the L1₀-FeNi formation mechanism has been studied.It is found the L1₀-FeNi in annealed samples at 400 ℃ mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 60 0 C lower than the measured onset temperature of the second stage with a5 0 C/min heating rate.Annealing at 400 0 C after fully crystallization still caused a slight increase of coercivity,which was probably contributed by the limited transformation from other high temperature crystalline phases towards L1₀ phase,or the removal of B from L1₀ lattice and improvement of the ordering quality of L1₀ phase due to the reduced temperature from520 ℃ to 400 ℃.The first stage of crystallization has hardly direct contribution to L1₀-FeNi formation.Ab initio simulations show that the addition of Si or Co in L1₀-FeNi has the effect of enhancing the thermal stability of L1₀ phase without seriously deteriorating its magnetic hardness.The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects.The approaches of synthesizing L1₀-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.更多还原