High coercivity was obtained in bulk RE(Dy) Fe C(B) alloys with RE=Nd, Pr and Mm. In the as cast state, the samples show a negligible coercivity H ci . Magnetic hardening takes place when annealing the as ...High coercivity was obtained in bulk RE(Dy) Fe C(B) alloys with RE=Nd, Pr and Mm. In the as cast state, the samples show a negligible coercivity H ci . Magnetic hardening takes place when annealing the as cast alloys at around 1173 K for several hours, which produces an H ci greater than 1200 kA·m -1 . Boron appears to be very important for achieving high coercivity, which is found to increase with increasing Dy content. SEM studies show a very small grain size at around 2 μm. X ray diffraction and TEM studies reveal the existence of multiphases after annealing. They are RE 2Fe 14 (B,C), RE 2Fe 3C x , alpha Fe(RE) and RE 2Fe 17 (B,C) in order of their amounts. The carbide RE 2Fe 3C x has a complicated hexagonal structure with a =0.468 nm and c =0.795 nm.展开更多
A new technique-series electro-pulse discharg e (SEPD)-was developed as a kind of surface coating process. In this technique, both positive and negative poles of a pulse power were used as the depositing electrodes...A new technique-series electro-pulse discharg e (SEPD)-was developed as a kind of surface coating process. In this technique, both positive and negative poles of a pulse power were used as the depositing electrodes with the substrate allo y as an induction electrode. Micro-crystalline Co-Cr and Co-Cr dispersed wit h Y 2O 3 coatings were deposited on Fe-18Cr-8Ni stainless steel surface by using Co30Cr alloy as the depositing electrodes. Oxidation at 950 ℃ in ambie nt air shows that these coatings greatly improve the oxidation resistance of the steel. The addition of dispersed Y 2O 3 nano-particles into the alloy coati ngs was found to further reduce the scaling rate and enhance the adhesion of oxi de scales.展开更多
In language learning,psychological aspects are of extreme importance and need to be taken into account.Among various psychological aspects,memory requirements and motivation are two crucial ones in EFL meterial design.
文摘High coercivity was obtained in bulk RE(Dy) Fe C(B) alloys with RE=Nd, Pr and Mm. In the as cast state, the samples show a negligible coercivity H ci . Magnetic hardening takes place when annealing the as cast alloys at around 1173 K for several hours, which produces an H ci greater than 1200 kA·m -1 . Boron appears to be very important for achieving high coercivity, which is found to increase with increasing Dy content. SEM studies show a very small grain size at around 2 μm. X ray diffraction and TEM studies reveal the existence of multiphases after annealing. They are RE 2Fe 14 (B,C), RE 2Fe 3C x , alpha Fe(RE) and RE 2Fe 17 (B,C) in order of their amounts. The carbide RE 2Fe 3C x has a complicated hexagonal structure with a =0.468 nm and c =0.795 nm.
文摘A new technique-series electro-pulse discharg e (SEPD)-was developed as a kind of surface coating process. In this technique, both positive and negative poles of a pulse power were used as the depositing electrodes with the substrate allo y as an induction electrode. Micro-crystalline Co-Cr and Co-Cr dispersed wit h Y 2O 3 coatings were deposited on Fe-18Cr-8Ni stainless steel surface by using Co30Cr alloy as the depositing electrodes. Oxidation at 950 ℃ in ambie nt air shows that these coatings greatly improve the oxidation resistance of the steel. The addition of dispersed Y 2O 3 nano-particles into the alloy coati ngs was found to further reduce the scaling rate and enhance the adhesion of oxi de scales.
文摘In language learning,psychological aspects are of extreme importance and need to be taken into account.Among various psychological aspects,memory requirements and motivation are two crucial ones in EFL meterial design.
