A Hybrid ON/OFF Method for Fast Solution of Electromagnetic Inverse Problems Based on Topological Sensitivity

The dynamic magnetostriction characteristics of an Fe-based nanocrystalline FeCuNbSiB alloy are investigated as a function of the dc bias magnetic field. The experimental results show that the piezomagnetic coefficient of FeCuNbSiB is about 2.1 times higher than that of Terfenol-D at the low dc magnetic bias H dc = 46 Oe. Moreover, FeCuNbSiB has a large resonant dynamic strain coefficient at quite low H dc due to a high mechanical quality factor, which is 3-5 times greater than that of Terfenol-D at the same low H dc . Based on such magnetostriction characteristics, we fabricate a new type of transducer with FeCuNbSiB/PZT-8/FeCuNbSiB. Its maximum resonant magnetoelectric voltage coefficient achieves ~10 V/Oe. The ME output power reaches 331.8 μW at an optimum load resistance of 7 kΩ under 0.4 Oe ac magnetic field, which is 50 times higher than that of the previous ultrasonic-horn-substrate composite transducer and it decreases the size by nearly 86%. The performance indicate that the FeCuNbSiB/PZT-8/FeCuNbSiB transducer is promising for application in highly efficient magnetoelectric energy conversion.

Dynamic Magnetostriction Characteristics of an Fe-Based Nanocrystalline FeCuNbSiB Alloy

Chen¹,

Li²,

Wen³

2011

Anisotropic Mechanical Properties of Pr(Co,In)₅-type Compounds and Their Relation to Texture Formation in Die-upset Magnets

Kwon

Kim²,

Yu³

2011

Die-upset magnets from a mechanically-milled Pr(Co,In) 5 -type alloy are known to have a peculiar texture; the easy magnetization axis (c-axis) is perpendicular to the pressing direction. This peculiar texture is thought to be linked closely to the anisotropic mechanical properties of Pr(Co,In) 5 -type hexagonal compounds. The hardness of the Pr(Co,In) 5 -type crystal was measured using selectively grown grains in an annealed Pr 17 Co 82 In 1 alloy button, and the crystallographic orientation was determined by observing the magnetic domain image. The hardness (549 VHN) on the plane with a 'cogwheel'-type domain image was significantly higher than that (510 VHN) on the plane with a 'cigar'-type domain image, indicating that the inter-layer bonding force between the (000l) basal planes is stronger than that between the (hki0) planes. This suggests that the most probable slip plane is the (hki0) plane parallel to the c-axis. During die-upsetting of the Pr(Co,In) 5 -type alloys the deformation proceeds by (hki0) plane slip, and the c-axis rotates to ultimately become oriented perpendicular to the pressing direction. It is proposed that the peculiar texture in the die-upset Pr(Co,In) 5 -type magnets is probably developed by slip deformation of the (hki0) plane of the Pr(Co,In) 5 -type grains.

Effect of Isothermal Aging on the Magnetic Properties of 1Cr-0.5Mo Steel

Kim¹,

Ryu²,

Lee³

et al. 2011

Magnetic properties and Rockwell hardness of 1Cr-0.5Mo steel have been investigated as a function of isothermal aging time. Our results showed that coercivity, hysteresis loss and Rockwell hardness in the aged samples decreased as aging time increased. This phenomenon was analyzed using optical microscopy and scanning electron microscopy. A significant diffusion of Cr and Mo atoms formed M 2 C and M 7 C carbides, lowering the matrix strength. M 2 C and M 7 C carbides partially segregated inside grains, diffused into grain boundaries, and finally resulted in a soft ferrite matrix and a hard grain boundary. The magnetic and mechanical softening of the matrix is likely to govern the properties of the sample more than the hardening of the grain boundary by carbide precipitations.