High-coercivity decomposition in Fe-(15, 23)%Co-30%Cr-3%Mo-0.5% Ti alloys

2009 ◽  
Vol 2009 (2) ◽  
pp. 160-163 ◽  
Author(s):  
V. S. Shubakov
Keyword(s):  
1991 ◽  
Vol 133 ◽  
pp. 147-150 ◽  
Author(s):  
J. Wecker ◽  
M. Katter ◽  
L. Schultz

Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.


Author(s):  
N. Qiu ◽  
J. E. Wittig

PtCo hard magnets have specialized applications owing to their relatively high coercivity combined with corrosion resistance and ductility. Increased intrinsic coercivity has been recently obtained by rapid solidification processing of PtCo alloys containing boron. After rapid solidification by double anvil splat quenching and subsequent annealing for 30 minutes at 650°C, an alloy with composition Pt42Co45B13 (at.%) exhibited intrinsic coercivity up to 14kOe. This represents a significant improvement compared to the average coercivities in conventional binary PtCo alloys of 5 to 8 kOe.Rapidly solidified specimens of Pt42Co45B13 (at.%) were annealed at 650°C and 800°C for 30 minutes. The magnetic behavior was characterized by measuring the coercive force (Hc). Samples for TEM analysis were mechanically thinned to 100 μm, dimpled to about 30 nm, and ion milled to electron transparency in a Gatan Duomill at 5 kV and 1 mA gun current. The incident ion beam angle was set at 15° and the samples were liquid nitrogen cooled during milling. These samples were analyzed with a Philips CM20T TEM/STEM operated at 200 kV.


Author(s):  
T. P. Nolan

Thin film magnetic media are being used as low cost, high density forms of information storage. The development of this technology requires the study, at the sub-micron level, of morphological, crystallographic, and magnetic properties, throughout the depth of the deposited films. As the microstructure becomes increasingly fine, widi grain sizes approaching 100Å, the unique characterization capabilities of transmission electron microscopy (TEM) have become indispensable to the analysis of such thin film magnetic media.Films were deposited at 225°C, on two NiP plated Al substrates, one polished, and one circumferentially textured with a mean roughness of 55Å. Three layers, a 750Å chromium underlayer, a 600Å layer of magnetic alloy of composition Co84Cr14Ta2, and a 300Å amorphous carbon overcoat were then sputter deposited using a dc magnetron system at a power of 1kW, in a chamber evacuated below 10-6 torr and filled to 12μm Ar pressure. The textured medium is presently used in industry owing to its high coercivity, Hc, and relatively low noise. One important feature is that the coercivity in the circumferential read/write direction is significandy higher than that in the radial direction.


1984 ◽  
Vol 45 (C9) ◽  
pp. C9-417-C9-422
Author(s):  
A. Jimbo ◽  
T. Hashizume ◽  
T. Sakurai ◽  
K. Al-Saleh ◽  
H. W. Pickering
Keyword(s):  

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1275-C8-1276
Author(s):  
K. Sumiyama ◽  
H. Yasuda ◽  
Y. Nakamura

2019 ◽  
Author(s):  
Xiao Han ◽  
Hoyun Won ◽  
Minyeong Choi ◽  
Liping Guo ◽  
Zhongqi Liu ◽  
...  

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