| 1. |
- Adcox, K, et al.
(författare)
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Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX Collaboration
- 2005
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Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 757:1-2, s. 184-283
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Forskningsöversikt (refereegranskat)abstract
- Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (PT), elliptic flow, two-particle correlations, nonstatistical fluctuations, and suppression of particle production at high PT. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.
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| 2. |
- Tian, Jianjun, et al.
(författare)
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Behavior of residual carbon in Sm(Co, Fe, Cu, Zr)z permanent magnets
- 2007
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 440:1-2, s. 89-93
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Tidskriftsartikel (refereegranskat)abstract
- When sintered Sm(Co, Fe, Cu, Zr)z permanent magnets are prepared by metal injection molding, some organic binders are added in alloy powder, which leads to much residual carbon in the magnets. The residual carbon decreases magnetic properties and destroys the microstructure of the magnets. In this paper, the behavior of carbon in Sm(Co, Fe, Cu, Zr)z permanent magnets has been studied. The results indicate that Sm(Co, Fe, Cu, Zr)z magnets can keep excellent magnetic properties when the carbon content is below 0.1 wt.%: Br ≥ 10 kGs, Hcj ≥ 22 kOe, BHmax ≥ 25 MGOe. When the carbon content is above 0.1 wt.%, Br, Hcj and BHmax decrease with increasing carbon content evidently. Carbon consumes Zr content and forms ZrC, which reduces the volume fraction of the lamella and Sm(Co, Cu)5 phases. Thus, the cell size increases and the cellular microstructure deteriorates. When the carbon content reaches 0.43 wt.%, there is not enough Sm(Co, Cu)5 phase to form a uniform cellular microstructure. Br, Hcj and BHmax are approximate to zero. Since carbon has little influence on the content of Sm2(Co, Fe)17 phase, Ms can keep a high value (≥100 emu/g). ZrC has high melting point (3420 °C) and acts as dispersion particle in the magnets, which prevents the grains of SEM structure growing and reduces the liquid content of green compacts during sintering. Therefore, the density of the magnets decreases
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| 3. |
- Tian, Jian-jun, et al.
(författare)
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Influence of heat treatment on fracture and magnetic properties of radially oriented Sm 2 Co 17 permanent magnets
- 2007
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Ingår i: Transactions of Nonferrous Metals Society of China. - 1003-6326 .- 2210-3384. ; 17:3, s. 491-495
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Tidskriftsartikel (refereegranskat)abstract
- The quenching, fracture and aging treatment of radially oriented Sm2Co17 ring magnets were investigated. The results indicate that the ring magnets have obvious anisotropy of thermal expansion, which easily leads to the splits of the magnets during quenching. The fracture is brittle cleavage fracture. The difference (δa) of the expansion coefficient reaches the maximum value at 800–850 °C. So, various quenching processes at different steps are adopted in order to reduce the splits. When the magnets are aged. 1:5 phase precipitates from the 2:17 matrix phase and forms a cellular microstructure with 2:17 phase. BHmax and 3Hc reach the maximum value 226 kJ/m3 and 2170 kA/m after being aged at 850 °C for 4 h and 8 h, respectively. The aging treatment at 850 °C has little influence on remanence(Br), which can always keep a high value (≥1.0 T). Through appropriate heat treatment, the ring magnets have uniform cellular microstructure and excellent magnetic properties: Br1.0T, 3Hc≥2 100 kA/m, BHmax≥220 kJ/m3.
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| 4. |
- Tian, Jianjun, et al.
(författare)
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Magnetic properties and microstructure of radially oriented Sm (Co, Fe, Cu, Zr) z ring magnets
- 2007
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 61:30, s. 5271-5274
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Tidskriftsartikel (refereegranskat)abstract
- Radially oriented Sm(Co,Fe,Cu,Zr)z ring magnets are prepared by powder metallurgy with appropriate magnetic field molding, sintering process and aging treatment. The results indicate that radially oriented Sm(Co,Fe,Cu,Zr)z ring magnets have obvious anisotropy of thermal expansion and sintering shrinkage, which easily lead to the splits and deformation of the ring magnets. So, slow heating, vacuum pre-sintering in sintering process and various quenching processes at different steps during quenching are adopted. The magnets have excellent magnetic properties: Br = 10.8 kGs, Hcj = 27.6 kOe, BHmax = 28.1 MGOe. Besides, there is a uniform magnetization field on the surface of the ring magnets. The average surface magnetization field (View the MathML sourceBs―) is 1.502 kGs. The deviation from average (α) is only 4.2%. The microstructure of the magnets consists of a mixture of homogeneous cellular and lamella structures.
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