Compositional variation of amorphous phase controlled coercivity of Nd ₆₀ Fe ₃₀ Al ₁₀ alloy

The coercivity of Nd-Fe-Al amorphous ferromagnetic materials originates from the combination of magnetic interaction and strong pinning of domain walls. Using Nd ₆₀ Fe ₃₀ Al ₁₀ alloys made under three cooling rates, we discovered an important microstructure parameter that can be used to strengthen interaction and pinning. By tuning the variations of composition difference between Nd-rich and Fe-rich amorphous regions, we enhanced the magnetic interaction and increased maximum restoring force per pin of Nd nanocrystals (with size <30 nm embedded in amorphous matrix). We were, however, not able to change pinning force by changing the grain morphology and the size of Nd nanocrystals (<30 nm).