Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《材料研究学报》
Abstract： The effect of Bi-content on microstructure evolution of Al-Bi monotectic alloy and solidification progress ofmiscibility gap under the action of gravity was studied by air cooling to desired temperatures and thenquenching, as well as bynumerical simulation. The average diameter and volume fraction of Bi-rich droplets in Al-10%Bi monotectic alloy are 1.1 and 12.8 times of those in Al-5%Bi monotectic alloyrespectively. A huge amount of large-size drops rich inBi gather in the lower part of Al-10% Bialloywith low solidification uniformity.The average size of drops rich in Bi in the alloy of Al-5%Bi with a uniform solidification; There's no large-size drops rich in Bi in the solidifiedmonotecticalloy with Al-3.4%Bi, and its solidification is uniform.The analysis demonstrates that the increase of the amount of Bi-rich phase may enhance the gravity action on the drops, thereby aggravate the solidification process with separation and decomposition of liquid phasesin the immiscible area, and enlargethe size and number of drops rich in Bi, whilethe synergistic action of Ostwald ripening and collision coagulation of drops yielda huge amount of large-size drops rich in Bi gathering in the lower part of the solidifying alloy, thus aggravates the macro segregation of the solidified monotectic alloy.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： In order to increase the magnetic properties and realize the essential applications in magnetic recording and spintronics devices, it is significant to control the growth mode and grain size of Fe films. In this work, the effects of a high magnetic field (HMF) on the growth and magnetic properties of Fe thin films with different grain sizes by using physics vapor deposition were explored. The decreased grain sizes are obtained by increasing the evaporation source temperatures. It is found that when the evaporation source temperature is 1440 ℃, the grains of film are fine. The growth mode is changed from layered to columnar by HMF. And HMF effectively reduces the defects of Fe film. When the evaporation source temperature is 1400 and 1350 ℃, the grains of films are large. HMF does not change the columnar growth mode of films. However, the width of columns is improved by a HMF. Additionally, HMF increases the average particle (composed of the grains) and grain size of Fe films with different grain sizes.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： Oscillation marks are closely related to the surface quality of bloom. Excellent surface quality of bloom is essential assurance of the technology of continuous casting and rolling. The improvement of heat transfer process through mold is beneficial to alleviate oscillation marks. A new method of inhibiting formation of oscillation marks in continuous casting, namely spraying or embedding thermal barrier coatings above mold meniscus (TBCMM) was proposed, by which the temperature and heat flux fluctuation of meniscus was reduced, and then the surface quality of strands was improved. Using an one-dimensional heat transfer simulating apparatus, the effect of location of thermal barrier coatings on heat transfer near meniscus was investigated, and the possible mechanism of TBCMM on inhibiting formation of oscillation marks was also discussed. With a dip simulator for continuous casting, lower melt point Sn-12.5%Pb alloy was casted with thermal barrier coating (TBC) and without TBC molds respectively, and the temperature fluctuation was also measured. The heat flux near meniscus in mold and the oscillation marks morphology on strands confirm the effectiveness of the proposed TBCMM. Finally, in a pilot continuous caster, casting experiments of steel with TBCMM was conducted, and the oscillation marks on billet surface were alleviated or removed.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Silicon steel thin strip was firstly surface shot peened, then cold rolled and finally siliconized by pack cementation process, The microstructural evolution was examined of the steel with the treatment processing. Results show that shot peening can induce the formation of noncrystalline (about 10nm in size) in the top surface layer, the grain size of the noncrystalline increases slightly after cold rolling. A compound layer can be obtained after siliconizing at 500oC in Si powder+halide on the shot peened and cold roll steel strip, its thickness increases with the increasing temperature and holding time, however on which the halide content exhibits little effect. After siliconizing at lower temperature the compound layer consists of single phase Fe3Si, and the increase of temperature, holding time and halide content is helpful for the formation of FeSi phase.
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