High coercivity nanocrystalline YCo5 powders produced by mechanical milling

2003 ◽  
Vol 127 (7) ◽  
pp. 527-530 ◽  
Author(s):  
J.L. Sánchez Ll ◽  
J.T. Elizalde-Galindo ◽  
J.A. Matutes-Aquino
Keyword(s):  
Mechanical Milling ◽  
High Coercivity

High coercivity in nanostructured PrCo5-based powders produced by mechanical milling and subsequent annealing

1999 ◽  
Vol 75 (20) ◽  
pp. 3165-3167 ◽  
Author(s):  
Zhongmin Chen ◽  
X. Meng-Burany ◽  
G. C. Hadjipanayis
Keyword(s):  
Mechanical Milling ◽  
Subsequent Annealing ◽  
High Coercivity

scholarly journals High coercivity induced by mechanical milling in cobalt ferrite powders

2013 ◽  
Vol 344 ◽  
pp. 182-187 ◽  
Author(s):  
A.S. Ponce ◽  
E.F. Chagas ◽  
R.J. Prado ◽  
C.H.M. Fernandes ◽  
A.J. Terezo ◽  
...  
Keyword(s):  
Mechanical Milling ◽  
Cobalt Ferrite ◽  
High Coercivity

Magnetic Hardening of Mechanically Alloyed Pr2Co7

2012 ◽  
Vol 1471 ◽  
Author(s):  
L. Bessais ◽  
R. Fersi ◽  
M. Cabié ◽  
N. Mliki
Keyword(s):  
Magnetic Properties ◽  
Mechanical Milling ◽  
Annealing Temperature ◽  
High Vacuum ◽  
Anisotropy Field ◽  
Milling Process ◽  
Subsequent Annealing ◽  
High Coercivity ◽  
Mechanically Alloyed ◽  
Transmission Electron

ABSTRACTThe Pr2Co7 alloys are known to crystallize in two polymorphic forms: a hexagonal of the Ce2Ni7 type structure and a rhombohedral of the Gd2Co7 one. They were synthesized by mechanical milling and subsequent annealing in high vacuum. In this work, we focus on the structural study of these phases using X-ray diffraction and transmission electron microscopy. Also, we present the evolution of magnetic properties of these compounds vs the annealing temperature. The coercivity increases with annealing temperature reaching a maximum for TA = 800 °C. The highest is equal to 18 kOe at 293 K and 23 kOe at 10 K. The high magnetic properties observed in these nanostructured Pr2Co7 intermetallic alloys have their origin in its relatively high uniaxial magnetocrystalline anisotropy field, and in the homogeneous nanostructure developed by mechanical milling process and subsequent annealing. This high coercivity is attributed to the high anisotropy field of the Pr2Co7 phase and its nanoscale grain size. This leads to the formation of a magnetically hard Pr2Co7 phase.

High-coercivity Nd-Fe-B Powders Obtained by High-Temperature Milling

2014 ◽  
Vol 59 (1) ◽  
pp. 47-50 ◽  
Author(s):  
W. Kaszuwara ◽  
B. Michalski ◽  
P. Orlowski
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
The Other ◽  
Nanocrystalline Powders ◽  
High Coercivity ◽  
Milling Temperature ◽  
Constituent Elements ◽  
Hard Magnetic Properties

Abstract The possibility of employing high temperature milling (600°C) for the production of highly coercive Nd-Fe-B powders was examined. The materials were the Nd12Fe82B6, alloy which was subjected to mechanical milling and the powders of the constituent elements of this alloy which were processed by mechanical alloying. The processes were conducted in the two variants: the first variant consisted of mechanical milling performed at a high temperature which was maintained during the entire process, and the other variant included preliminary milling carried out at room temperature and then the milling temperature was increased. All the processes gave nanocrystalline powders with hard magnetic properties. The powders produced by mechanical milling had better properties than those produced by mechanical] alloying as they were more homogeneous and contained smaller amounts of the α-Fe phase.

Annealing Effect on Microstructure and Coercivity of YCo5 Nanoparticles Obtained by Mechanical Milling

2009 ◽  
Vol 68 ◽  
pp. 122-126
Author(s):  
José Trinidad Elizalde Galindo ◽  
Reiko Sato Turtelli ◽  
Roland Grössinger ◽  
José Andrés Matutes-Aquino
Keyword(s):  
Heat Treatment ◽  
Exchange Interaction ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Annealing Effect ◽  
Subsequent Heat Treatment ◽  
High Coercivity ◽  
Crystallite Sizes

Nanocrystalline YCo5 powders with high coercivity were prepared by mechanical milling and subsequent heat treatment at 820 °C for different annealing times, ta = 2.5, 3.0, 3.5 and 4.5 min, obtaining average crystallite sizes of <D>  17, 19, 32 and 39 nm., respectively. The coercivity values were determined from the hysteresis loops measured at maxima fields of Hm = 5 and 20 T. The highest coercivity was obtained for the sample exhibiting <D>  19 nm, where at room temperature and Hm = 5 T, the coercivity value is of 9.0 kOe. At 77 K and Hm = 5 T, the coercivity increase to 11.8 kOe and for Hm = 20 T, a higher value such as 13.1 kOe was found. The Ms/Mr ratio is enhanced to 0.62 indicating the occurrence of exchange interaction among nanocrystalline magnets.

Lorentz electron microscopy of magnetic domains in rapidly solidified and annealed Pt-Co-B alloys

1991 ◽  
Vol 49 ◽  
pp. 784-785
Author(s):  
N. Qiu ◽  
J. E. Wittig
Keyword(s):  
Rapid Solidification ◽  
Ion Beam ◽  
Magnetic Behavior ◽  
High Coercivity ◽  
Magnetic Domains ◽  
Beam Angle ◽  
Tem Analysis ◽  
Intrinsic Coercivity ◽  
Hard Magnets ◽  
Rapidly Solidified

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.

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