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The development of Fe73.5Si13.5B9Nb3Cu1 (FINEMET) by Yoshizawa et al. and Fe88Zr7B4Cu1 (NANOPERM) by Inoue et al. have shown that nanocrystalline microstructures can play an important role in the production of materials with outstanding soft magnetic properties. The FINEMET and NANOPERM materials rely on nanocrystalline α-Fe3Si and α-Fe, respectively, for their soft magnetic properties. The magnetic properties of a new class of nanocrystalline magnets are described herein. These alloys with a composition of (Fe,Co)–M–B–Cu (where M=Zr and Hf) are based on the α- and α′-FeCo phases, have been named HITPERM magnets, and offer large magnetic inductions to elevated temperatures. This report focuses on thermomagnetic properties, alternating current (ac) magnetic response, and unambiguous evidence of α′-FeCo as the nanocrystalline ferromagnetic phase, as supported by synchrotron x-ray diffraction. Synchrotron data have distinguished between the HITPERM alloy, with nanocrystallites having a B2 structure from the FINEMET alloys, with the D03 structure, and NANOPERM alloys, with the A2 structure. Thermomagnetic data shows high magnetization to persist to the α→γ phase transformation at 980 °C. The room temperature ac permeability has been found to maintain a high value of 1800 up to a frequency of ∼2 kHz. The room temperature core loss has also been shown to be competitive with that of commercial high temperature alloys with a value of 1 W/g at BS=10 kG and f=1 kHz.

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Effects of Cu content and preaging treatments on precipitation sequence and artificial aging response in aluminum alloy 6022 were investigated using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness tests. It was found that Cu induces the formation of Q and its precursor metastable phases and has a beneficial effect on the kinetics of artificial aging. For the alloy with 0.07 wt pct Cu, the precipitation sequence is GP zones → needlelike ␤ Љ → rodlike ␤ Ј ϩ lathlike QЈ → ␤ ϩ Si. On the other hand, the precipitation sequence in the alloy with 0.91 wt pct Cu is GP zones → needlelike ␤ Љ → lathlike QЈ → Q ϩ Si. For the artificial aging condition of 20 minutes at 175 ЊC, which is the typical automotive paint bake condition, suitable preaging treatments were found to significantly reduce the detrimental effect of the natural aging on artificial aging response.