High coercivity FePt–C bulk magnet processed by spark plasma sintering and hot deformation

2010 ◽  
Vol 322 (21) ◽  
pp. 3423-3427 ◽  
Author(s):  
R. Gopalan ◽  
T. Ohkubo ◽  
K. Hono
Keyword(s):  
Spark Plasma Sintering ◽  
Hot Deformation ◽  
High Coercivity ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Bulk Magnet

scholarly journals Spark Plasma Sintering as an Effective Texturing Tool for Reprocessing Recycled HDDR Nd-Fe-B Magnets with Lossless Coercivity

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 418 ◽  
Author(s):  
Awais Ikram ◽  
Muhammad Awais ◽  
Richard Sheridan ◽  
Allan Walton ◽  
Spomenka Kobe ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Hot Deformation ◽  
Low Pressure ◽  
Texture Development ◽  
High Coercivity ◽  
Processing Temperature ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Better Than

The low-pressure hot-deformation methodology was applied to reprocess the nanocrystalline hydrogenation–disproportionation–desorption–recombination (HDDR) Nd-Fe-B powders from end-of-life (EOL) permanent magnets’ waste to determine the mechanism of texture development and the resultant improvement in remanence (and BHmax) in the recycled material. Both the hot-pressed and hot-deformed magnets produced via spark plasma sintering (SPS) were compared in terms of their magnetic properties with respect to forging pressures. Also, a comparison was established with the microstructure to cite the effectiveness of texture development at low deformation rates and pressures which is pivotal for retaining high coercivity. The hot-pressed magnets maintain the high coercivity (better than 100%) of the original recycled powder due to the control of SPS conditions. The hot deformation pressure was varied from 100–150 MPa at 750 °C processing temperature to identify the optimal texture development in the sintered HDDR Nd-Fe-B magnets. The effect of post-hot-deformation thermal treatment was also investigated, which helped in boosting the overall magnetic properties and better than the recycled feedstock. This low-pressure hot deformation process improved the remanence of the hot-pressed magnet by 11% over the starting recycled powder. The Mr/MS ratio which was 0.5 for the hot-pressed magnets increased to 0.64 for the magnets hot-deformed at 150 MPa. Also, a 55% reduction in height of the sample was achieved with the c-axis texture, indicating approximately 23% higher remanence over the isotropic hot-pressed magnets. After hot deformation, the intrinsic coercivity (HCi) of 960 kA/m and the remanence (Br) value of 1.01 T at 150 MPa is indicative that the controlled SPS reprocessing technique can prevent microstructure related losses in the magnetic properties of the recycled materials. This route also suggests that the scrap Nd-Fe-B magnets can be treated with recoverable magnetic properties subsequently via HDDR technique and controlled hot deformation with a follow-up annealing.

scholarly journals Microstructure evolution of TC4 powder by spark plasma sintering after hot deformation

2020 ◽  
Vol 39 (1) ◽  
pp. 457-465
Author(s):  
Jiangpeng Yan ◽  
Zhimin Zhang ◽  
Jian Xu ◽  
Yaojin Wu ◽  
Xi Zhao ◽  
...  
Keyword(s):  
Strain Rate ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Hot Deformation ◽  
Tc4 Titanium Alloy ◽  
Weave Structure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Average Relative Density ◽  
Low Strain Rate

AbstractThe cylindrical samples of TC4 titanium alloy prepared by spark plasma sintering (SPS) were compressed with hot deformation of 70% on the thermosimulation machine of Gleeble-1500. The temperature of the processes ranged from 850°C to 1,050°C, and the strain rates varied between 0.001 and 5 s−1. The relative density of the sintered and compressed samples was measured by the Archimedes principle. During hot deformation, the microstructure of the sample was observed. The results show that the average relative density of the samples was 90.2% after SPS. And the relative density was about 98% after the hot deformation of 70%. Under high temperature (>950°C), the sensitivity of flow stress to temperature was reduced. At low strain rate (0.001 s−1), the increase in the deformation temperature promoted the growth of dynamic recrystallization (DRX). At the same temperature, the increase in strain rate slowed down the growth of DRX grains. And the variation tendency was shown from the basket-weave structure to the Widmanstätten structure at a low strain rate (<0.1 s−1), with increase in the strain rate.

scholarly journals Hydrogen Decrepitation and Spark Plasma Sintering to Produce Recycled SmCo5 Magnets With High Coercivity

2018 ◽  
Vol 9 ◽  
pp. 1-4 ◽  
Author(s):  
Anas Eldosouky ◽  
Awais Ikram ◽  
Muhammad Farhan Mehmood ◽  
Xuan Xu ◽  
Saso Sturm ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
High Coercivity ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Hydrogen Decrepitation

Structures and magnetic properties of Sm-Fe-N bulk magnets produced by the spark plasma sintering method

2007 ◽  
Vol 22 (11) ◽  
pp. 3130-3136 ◽  
Author(s):  
Tetsuji Saito
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Bulk Material ◽  
Decomposition Temperature ◽  
High Coercivity ◽  
Bulk Materials ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method ◽  
N Powder

Sm-Fe-N powders were successfully consolidated at 873 K and below by the spark plasma sintering (SPS) method. Although the decomposition temperature of the hard magnetic Sm2Fe17N3 phase has been reported to be 873 K, partial decomposition of the Sm2Fe17N3 phase was noted in the bulk materials obtained by sintering at below that temperature. The resultant bulk materials showed a coercivity of around 0.24 MAm−1, significantly lower than that of the original Sm-Fe-N powder. It was found that decomposition of the Sm2Fe17N3 phase in the SPS method was significantly lowered by the addition of a small amount of Zn powder to the Sm-Fe-N powder. The bulk material obtained by sintering a mixture of Sm-Fe-N and Zn powder (10%Zn) at 723 K exhibited high coercivity, comparable with that of the original Sm-Fe-N powder.

Structures and magnetic properties of Nd–Fe–B bulk nanocomposite magnets produced by the spark plasma sintering method

2004 ◽  
Vol 19 (9) ◽  
pp. 2730-2737 ◽  
Author(s):  
Tetsuji Saito ◽  
Tomonari Takeuchi ◽  
Hiroyuki Kageyama
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Applied Pressure ◽  
High Coercivity ◽  
Bulk Materials ◽  
Soft Magnetic ◽  
Nanocomposite Magnets ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method

We studied the effects of the sintering temperature and applied pressure on Nd–Fe–B bulk nanocomposite magnets produced by the spark plasma sintering (SPS) method. Amorphous Nd4Fe77.5B18.5 melt-spun ribbons were successfully consolidated into bulk form by the SPS method. When sintered at 873 K under applied pressures between 30 and 70 MPa, the bulk materials consisted of nanocomposite materials with a soft magnetic Fe3B phase and hard magnetic Nd2Fe14B phase. The density and magnetic properties of the bulk materials sintered at 873 K were strongly dependent on the applied pressure during sintering. Bulk Nd4Fe77.5B18.5 nanocomposite magnets sintered at 873 K under an applied pressure of 70 MPa showed a high remanence of 9.3 kG with a high coercivity of 2.5 kOe.

Sign in / Sign up

Export Citation Format

Share Document