Shigang XIN
,
Zhaohua JIANC
,
Fuping WANG
,
Xiaohong WU
,
Liancheng ZHAO
,
Tadao SHIMIZU
材料科学技术（英）
The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAlO2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.
关键词:
Physica B-Condensed Matter
Magnetization and AC susceptibility measurements have been carried out to investigate the magnetic phase transition of Gd1-xDYxCo2 compounds. It is revealed that the type of the magnetic phase transition changes from second order to first order around x(c) = 0.8 with the increase of Dy concentration. A satisfactory explanation is offered in terms of the Inoue-Shimizu model. The exchange-enhanced susceptibility of the compounds within the exchange-enhanced paramagnetism model is in good agreement with the 3d-electrons susceptibility deduced by Inoue-Shimizu model. (C) 2003 Elsevier Science B.V. All rights reserved.
关键词:
Laves phase RCo2;magnetic phase transition;susceptibility;intermetallic compounds;order
Physica B-Condensed Matter
X-ray powder diffraction and magnetization measurements reveal that light rare earth and heavy rare earth have different effects on the structure, Curie temperature and magnetic phase transition of the compounds R(Co1-xGax)(2) (R = Nd, Gd, Tb, Dy) (x = 0.0-0.3). The lattice constant exhibits a giant increase with increasing Ga concentration in all compounds. The Curie temperature shows no variation for R = Nd, a monotonic decrease for R = Gd and a maximum for R=Tb and Dy, respectively. The Curie temperature is strongly related with volume expansion, in which a critical value of a(c) approximate to 7.26 Angstrom is reached. The observed magnetic transition in all compounds is well explained within the framework of the Inoue-Shimizu model. It is revealed that both the lattice constant and the Curie temperature have a strong relationship with the order of the magnetic phase transition. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
structure;Curie temperature;magnetic phase transition;itinerant-electron metamagnetism;intermetallic compounds;ac;susceptibility;order;temperature;behavior;r(co;yco2
