Junming LIU
,
Zhiguo LIU and Zhuangchun WU(National Laboratory of Solid State Microstructures
,
Nanjing University
,
Nanjing
,
210008
,
China)
材料科学技术（英）
A Monte-Carlo approach of cellular pattern evolution during directional solidification of a binary alloy has been carried out by imposing a non-uniform probability distribution of particle emission from the particle source, as an approach to the contribution of solute redistribution to the interface evolution. Both the bulk and interface diffusion have been involved in the simulation,and coarsening of the cellular patterns with time has been clearly revealed. The remarkable influence of the interface relaxation and the solute redistribution on the profile of solidifying interface has been presented.
关键词:
E DONG and Guoxing LIU (Department of Material Science and Engineering
,
Nanjing University of Science and Technology
,
Nanjing
,
210014
,
China)(To whom correspondence should be addressed)
材料科学技术（英）
In order to improve the homogeneity of the pseudo-alloy W-Cu used in a certain ordnance component. the formation of solid solution of W-Cu system with a positive heat of mixing by mechanical alloying (MA) has been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM).transmission electron microscopy (TEM ) and differential thermal analysis (DTA). It was found that the supersaturated solid solution phase formed in the whole investigated composition range from W90Cu10 to W60Cu40 (at.-%). although the systern W-Cu exhibits a total immiscibility in both solid and liquid states, A systematic investigation on W70Cu30 showed that a solid solubility of Cu in W increased with the milling time. The Iattice parameters of phase W decreased with the increasing of the milling time and solute content of Cu. The thermal stability of the solid solution was studied by DTA. It was found that the decomposition of solid solution. the recovery and the growth of the grain occurred over 2 50℃. The driving force of the solid solution W-Cu system by MA mainly comes from high density of defects bV ball milling, which would enhance the free energy of the system. The solution process is diffusion-controlled
关键词:
