Effect of Melt Quenching on Martensite Transformation in Fe-Ni Alloy

The main features of martensite transformation in melt-quenched Fe-31.4% Ni alloy on cooling below room temperature have been studied. It is found that the ribbon 50～60 μm thick, prepared by spinning technique, is a natural composite in which isothermal and surface martensite are not formed, while athermal martensite forms at lower temperature, all factors being the same, as compared to the alloy of the same composition and grain size, prepared by recrystallization.

Microstructure and magnetostrictive properties of Tb doped Fe–Ga bulk alloys prepared by melt quenching

The microstructure and magnetostrictive properties were investigated in the Tb doped Fe83Ga17-xTbx（x = 0.05, 0.10, 0.20, 0.30, 0.40, 0.50） bulk rods prepared by melt rapidly quenching. The partial solid solubility of Tb in the Fe-Ga matrix was preliminary detected by the lattice parameters and SEM observation. The matrix keeps A2 structure and the second phase appears surround the grain boundary as x C 0.1. h100 i preferred orientation is also observed for x = 0.1 sample along the axis of the quenched rod. The saturation magnetostriction first increases and maximum value reaches at x = 0.1, and then decreases with Tb addition increasing. The initial increase of the magnetostriction should be associated with the partial solution of Tb in the matrix, the maximum value at x = 0.1 should be attributed to the h100 i preferred orientation, and the decrease of the magnetostriction is correlated with the appearance of the second phase along the grain boundary.

Electrochemical impedance spectra of V_2O_5 xerogel films with intercalation of lithium ion

Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide xerogel films was simulated with an equivalent circuit model, which was derived from the mechanism of electrode reactions. Measured electrochemical impedance spectra at various electrode potentials were analyzed by using the complex non-linear least-squares fitting method. The results show that impedance spectra consist of 2 high-to- medium frequency depressed arcs and a low frequency straight line. The high frequency arc is attributed to the absorption reaction of lithium ions into the oxide film, the medium frequency arc is attributed to the charge transfer reaction at the vanadium oxide/electrolyte interface and the low frequency is characterized by a straight line with a phase angle of 45° corresponding to the diffusion of lithium ion through vanadium oxide phase. The experimental and calculated results are compared and discussed focusing on the electrochemical performance and the state of charge of the electrode. Moreover, the high consistence of the fitted values of the model to the experimental data indicates that this mathematical model does give a satisfying description of the intercalation process of vanadium pentoxide xerogel films.

Novel Preparation and XPS Analysis of V_2O_5 Xerogel

The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS spectrum difference of V 2O 5 xerogel when the powder of V 2O 5 was melting in air or in oxygen atmosphere.The results show that the different melting atmosphere has certain influences on the chemical valence of V 2O 5 xerogel.

Investigation on Phase Evolution of the ZnO-B2O3-SiO2 Glass Ceramics

ZnO-B2O3-SiO2-Al2O3-Na2O glass doped with nucleating agent TiO2 was prepared with melting-quenching method and the effect of nucleating agent on the crystallization behavior and phase evolution of this glass was investigated by differential thermal analysis（DTA）,X-ray diffraction（XRD）,and scanning electron microscopy（SEM）.The experimental results show that the glass transition temperature and the first crystallization temperature decrease from 630 ℃ and 765 ℃ to 595 ℃ and 740 ℃,respectively,with introduction of TiO2 into glass.There is no diffraction peaks in the XRD pattern but it is no longer transparent for the base glass without nucleating agent after heat treatment,which suggests the serious phase separation occurred,and the observation by SEM indicates that the phase separation is developed by nucleation and growth mechanism.However,there are two different crystals ZnAl2O4 and NaAlSiO4 present in the glass containing TiO2 after heat treating at 575 ℃ for 2 h and 740 ℃ for 6 h,respectively.What is interesting is that NaAlSiO4 disappears as the crystallization time at 740 ℃ increases from 6 h to 12 h,and more ZnAl2O4 crystal is formed,namely,the further formation of ZnAl2O4 is at cost of NaAlSiO4 with increasing crystallization time.And observation of the morphology of glass ceramics shows great difference with increasing crystallization time.Moreover,the ability of ZnO-B2O3-SiO2-Al2O3-Na2O glass ceramics against attacking of 1M HCl solution is increased by the crystals precipitated in heat treatment process.

Advances in Investigation of Fe-based Glass-forming Alloy Melts

Continuous precision casting is an important trend in modern industrialization.Clustering effects in glassforming metallic liquids tremendously influence the properties of rapidly quenched ribbons;therefore,much attention has been paid to the study of Fe-based glass-forming melts at high temperatures.Recent investigations of these melts are categorized and reviewed.It is concluded that more efforts are still required to reveal the discipline of amorphization brought about by rapid quenching of Fe-based glass-forming melts.

Transport and physical properties of V_(2)O_(5)-P_(2)O_(5)-B_(2)O_(3) glasses doped with Dy_(2)O_(3)

We investigate the DC transport properties of 60V_(2)O_(5)-5P_(2)O_(5)-(35-x)B_(2)O_(3)-xDy_(2)O_(3)(x=0.4,0.6,0.8,1.0 and 1.2 mol%)glasses as function of temperature which were prepared using the conventional melt-quenching method.These glasses are characterised by thermo gravimetric-differential thermal analysis(TG-DTA).Activation energy(E_(DC))is obtained from Arrhenius plots of temperature-dependent DC conductivity,and it is found to be 0.30 eV for high conducting glass.In order to understand the role of Dy_(2)O_(3) in these glasses,the density and molar volume are investigated.The results show that molar volume of the glass increases with the increasing of Dy2O_(3) concentration.The ionic conductivity is found to be dominant over the electronic conductivity and varies between 82%and 96%.

Experimental Study on Factors that Influence the Diameter of Dry Granulated Particles

The development of heat recovery methods for dry granulation processes from blast furnace slag in the iron and steel industry is limited because of the high consumption of granulation energy during these processes.To determine the factors that influence the diameter of granulated particles,a paraffin test platform for gas quenching granulation was established.The influences of air velocity,air flow rate,liquid mass flow rate,and liquid pipe diameter on the final particle size and mass distribution were studied.Experimental results showed that the final particle size decreased(from 1.07 mm to 0.81 mm) with increasing air velocity(from 28.3 m/s to 113.2 m/s).However,when air velocity was higher than 60 m/s,its influence on particle diameter decreased significantly.The experimental data were analyzed using SPSS Statistics software,which indicated that the effect of air velocity on particle diameter was the most significant,followed by those of air flow and liquid pipe diameter.The effect of liquid mass flow was the least significant.