强磁场下Cu−Co难混溶合金凝固过程中晶体取向和性能的调控

对Cu50Co50合金在不同磁场强度下进行非平衡凝固实验,研究富钴相的取向、显微组织演化和磁性能。结果表明,凝固后相分离的棒状富钴相可以实现排列形态,在5 T强磁场下富钴相的晶体取向为111平行磁场方向。然而,发生二次液−液相分离的富铜相的取向没有受到HMF的显著影响。在0 T磁场下凝固的合金表现出近磁各向同性行为,而在5 T磁场下凝固的合金则表现出磁各向异性行为。合金的饱和磁化强度略有增加,矫顽力相应降低,这与富钴晶体的取向演化行为密切相关。

Evading strength−ductility trade-off of GH605 alloy using magnetic field-assisted undercooling treatment

Undercooling solidification under a magnetic field(UMF)is an effective way to tailor the microstructure and properties of Co-based alloys.In this study,by attributing to the UMF treatment,the strength−ductility trade-off dilemma in GH605 superalloy is successfully overcome.The UMF treatment can effectively refine the grains and increase the solid solubility,leading to the high yield strength.The main deformation mechanism in the as-forged alloy is dislocation slipping.By contrast,multiple deformation mechanisms,including stacking faults,twining,dislocation slipping,and their strong interactions are activated in the UMF-treated sample during compression deformation,which enhances the strength and ductility simultaneously.In addition,the precipitation of hard Laves phases along the grain boundaries can be obtained after UMF treatment,hindering crack propagation during compression deformation.

Epidemiological studies of esophageal cancer in the era of genome-wide association studies

Esophageal cancer(EC) caused about 395000 deaths in 2010. China has the most cases of EC and EC is the fourth leading cause of cancer death in China. Esophageal squamous cell carcinoma(ESCC) is the predominant histologic type(90%-95%), while the incidence of esophageal adenocarcinoma(EAC) remains extremely low in China. Traditional epidemiological studies have revealed that environmental carcinogens are risk factors for EC. Molecular epidemiological studies revealed that susceptibility to EC is influenced by both environmental and genetic risk factors. Of all the risk factors for EC, some are associated with the risk of ESCC and others with the risk of EAC. However, the details and mechanisms of risk factors involved in the process for EC are unclear. The advanced methods and techniques used in human genome studies bring a great opportunity for researchers to explore and identify the details of those risk factors or susceptibility genes involved inthe process of EC. Human genome epidemiology is a new branch of epidemiology, which leads the epidemiology study from the molecular epidemiology era to the era of genome wide association studies(GWAS). Here we review the epidemiological studies of EC(especially ESCC) in the era of GWAS, and provide an overview of the general risk factors and those genomic variants(genes, SNPs, miRNAs, proteins) involved in the process of ESCC.

Effect of high magnetic field on solidification microstructure evolution of a Cu-Fe immiscible alloy

The liquid phase separation behavior and the evolution of the solidification microstructure of a binary Cu_(50)Fe_(50) alloy were investigated under the conditions of without and with a 10 T magnetic field,with different undercooling during the solidification process.Results show that the combined effect of Stokes motion and Marangoni convection leads to the formation of the core-shell structure under the condition without the magnetic field.In addition,specific gravity segregation is reinforced by increasing the undercooling,resulting in Fe-rich phase drifts towards the sample edge.In the 10 T magnetic field,the Fe-rich phase is elongated in the parallel direction of the magnetic field under the action of demagnetization energy due to the difference of static magnetic energy and surface energy.In the vertical direction,through the action of Lorentz force,the convection in the melt is inhibited and Fe-rich phase becomes more dispersed.Meanwhile,the diffusion of the two phases and the coagulation of the Fe-rich phases are also restrained under the magnetic field,therefore,the phase volume fraction of the Fe-rich phase decreases at the same undercooling in the 10 T magnetic field.The magnetic field inhibits the segregation behavior in the vertical direction of the magnetic field,and at the same time,improves the gravitational segregation to a certain extent,which has a very important impact on microstructure regulation.

Liquid−liquid structure transition in metallic melt and its impact on solidification:A review

Understanding the nature of liquid structures and properties has always been a hot field in condensed matter physics and metallic materials science.The liquid is not homogeneous and the local structures inside change discontinuously with temperature,pressure,etc.The liquid will experience liquid−liquid structure transition under a certain condition.Liquid−liquid structure transition widely exists in many metals and alloys and plays an important role in the final microstructure and the properties of the solid alloys.This work provides a comprehensive review on this unique structure transition in the metallic liquid together with the recent progress of its impact on the following microstructure and properties after solidification.These effects are discussed by integrating them into different experimental results and theoretical considerations.The application of liquid−liquid structure transition as a strategy to tailor the properties of metals and alloys is proven to be practical and efficient.