Zhoushun ZHENG
,
Xuanhui QU
,
Yunping LI
,
Jianfeng GUO
材料科学技术（英）
A mathematical model of two-dimensional flows of PIM derived from the momentum, continuity equations and the heat transfer equation is obtained. The formula of calculating the flow conductance and the pressure equation are deduced when the no slip boundary condition is employed at the wall, and the pressure equation is a non-linear elliptic partial differential equation. The flow front locations, distribution of velocities, temperature and pressure are simulated by the finite element analysis software ANSYS. Simulation results indicate that it is in the final filled part that defects appear easily. The region in which the defects may occur during the PIM process can be predicted.
关键词:
Numerical simulation
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null
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Zhijian LIU
,
Zhiyou LI
,
Wei DUAN
,
Xuanhui QU
,
Baiyun HUANG
,
Siqi ZHANG
材料科学技术（英）
A LI-B alloy has been prepared using a pretreated amorphous B powder and pure Li ingot as starting materials by continually slow addition of B powder and intensified stirring in the process of melting. The microstructure and the discharge characteristic of the materials have been investigated. Results show that the problem of temperature control in synthesis would be modified by means of continual addition of B powder, the Li7B6 would be more finery distributed in the metal Li by means of intensified stirring. The discharge characteristic of the Li-B alloy using amorphous B as starting materials is almost the same with that of using crystalline B.
关键词:
Shaojun LIU
,
Xuanhui QU
,
Zhijiang LIU
,
Baiyun HUANG
材料科学技术（英）
The structure of Mo-15.16 Si, Mo-30 Si and Mo-36.3 Si (wt pct) elemental powder mixture during mechanical alloying was studied using electron microscopy and X-ray diffraction. It had been found that, in all the systems under study, silicon disappeared initially during mechanical alloying (MA). In the Mo-Si systems all products were in form of amorphous state after long time milling, but there were different intermediate products. MoSi2 and Mo5Si3 intermetallic compounds in the Mo-30Si and Mo-36.3Si (wt pct) were directly synthesized from elements through inter-diffussion process. The high density of defects and interface of nano-crystallines induced by ball milling would promote the reaction process. Only in the Mo-15.16Si (wt pct) system was Mo(Si) supersaturated solid solution formed as an intermediate product. Schematic free-energy diagram of Mo-Si system based on the thermodynamics was used to analyze the difference among the intermediate state products.
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