Влияние редкоземельных металлов на стеклообразующую способность и кристаллизацию аморфных сплавов CoFeSiBNb

In present work amorphous alloys Co48Fe25Si4B19Nb4-R (R = Nd, Sm, Tb, Yb) were obtained by planar flow casting in the form of ribbons with 3-5 mm wide and 35-45 μm thickness. It was found that crystallization process goes into two stages and depends on the used rare-earth addition and its content in the alloy by differential thermal analysis method. Glass-forming ability criteria were calculated. It is shown that paramagnetic Curie temperature of alloys in liquid state can be used as their a-priori criterion of glass-forming ability.

Influence of rare earth addition on the properties of AA6351 hybrid composites

Nowadays, the effect of the rare earth addition on the performance of aluminium matrix composites is a major interest for many researchers. The present research work emphasis is on the study of the effect of praseodymium oxide (rare earth element) addition on the performance of AA6351 hybrid composites. Silicon carbide and rice husk ash in the weight proportions of 6:2 were ball-milled with various weight percentages (0.4%, 0.8%, and 1.2%) of praseodymium oxide to have a consistent microstructure and combined density equivalent to the AA6351 matrix alloy. Further, AA6351 hybrid composites with the ball-milled reinforcement of silicon carbide, rice husk ash, and praseodymium oxide were produced using stir-casting technique. Physical, microstructural, mechanical, and tribological characterization were done to study the impact of praseodymium oxide addition on the developed hybrid composites. An increment of 2.61% in the density, 49.40% in the microhardness, and 19.78% in the ultimate tensile strength was recorded with the incorporation of 1.2 weight percentage of praseodymium oxide in the AA6351 hybrid composites. The wear rate of the developed composites also improved by 32.92% with the addition of praseodymium oxide. The results exhibited a remarkable improvement in the performance of the AA6351 hybrid composites with the addition of rare earth element.

Effect of Heterogeneous Nucleation on Removal of Arsenic from Molten Steel by Rare Earth Addition

Cleanliness control is an eternal theme to improve the properties of steel products. With the increasing recycling rates of scrap steel, the removal and stabilization of residual elements have become a vital issue for improving the performance of steel products. Thermodynamic and mismatch calculations plus laboratory experiments were carried out to study the heterogeneous nucleation phenomena of inclusions when lanthanum was employed to remove arsenic from molten steel and stabilize arsenic in solid steel. The effect of heterogeneous nucleation on the mechanism of arsenic removal was discussed. A series of heterogeneous nucleation phenomena of inclusions in the La-O-S-As system were discovered, and the heterogeneous nucleation among the inclusions turned out to be selective. As the vital product of arsenic removal, La-S-As is most likely to generate with LaS as heterogeneous nucleation cores, and its possible chemical formula turned out to be 3LaS⸱LaAs. Sulfur plays an essential role in removing arsenic from molten steel by adding lanthanum. It needs to control the initial sulfur content in an appropriate range, because the high initial content causes too much loss of rare earth, and the low initial content cannot produce LaS and La-S-As.

Effect of Ce-La on inclusion evolution in Al-killed high strength steel

The mechanism of inclusion evolution after rare earth addition based on oxide metallurgy was investigated experimentally and using thermodynamic calculations, where Ce-La was added to Al-killed high strength steel during Ruhrstahl-Heraeus refining to modify the oxide inclusions within the steel. The typical inclusions observed before Ce-La addition were spherical magnesium aluminate spinel inclusions. And fewer individual Al2O3 inclusions and Al2O3–TiOx inclusions were also observed. The addition of Ce-La led to transformation of MgO · Al2O3 spinel inclusions to (Ce,La)2O3, (Ce,La)2O2S and (Ce,La)2O2S + MgO · Al2O3 inclusions. Thermodynamic calculations indicated that Ce-La combined with dissolved oxygen and sulfur in molten steel to form rare earth inclusions, while the remainder of the Ce and La modified MgO · Al2O3 to (Ce,La)2O3 and (Ce,La)2O2S.