electric, magnetic composite effect on the solidification of metals

Title: electric, magnetic composite effect on the solidification of metals Author: Yu Jianbo Degree-granting units: Shanghai University Keywords: composite electromagnetic field;; strong magnetic field;; electromagnetic oscillations;; Alfven waves;; grain refinement;; aluminum Abstract: Microstructure refinement is to improve the mechanical properties of metallic materials and the use of effective means of performance. Numerous studies show that: in the gold
Solidification process is electromagnetic Magnetic lifter oscillations can exert control columnar grain, refined equiaxed, and even the formation of nearly spherical tissue. However, regarding the electromagnetic oscillations of the
The impact of metal solidification mechanism, the lack of systematic, regular study. In addition, previous studies using alternating / pulsed magnetic field, only
Limited to the application of oscillating electromagnetic field effects. In recent years with the development of superconducting magnets, strong static magnetic field of solidification by the people to pay attention, found strong
Magnetic field has multiple effects on the solidification of metal, strong magnetic field in the context of recombination current on the metal solidification will undoubtedly have more diverse than for external oscillator
With the use of these effects will refine and improve performance at all levels of the organization to open up new avenues, but so far research in this area is lacking.
This will be a strong magnetic field and AC Steady phase composite (composite, said the text field), examine the resulting electromagnetic oscillations, the metal flow of magnetic flux
Physical science and magnetic polarization effect and its effect on the aluminum alloy solidified structure of the mechanism, and then carry http://www.999magnet.com/products/131-magnetic-lifter out the practical application of research. Result
Show that: (1) Steady strong magnetic field and AC composite electromagnetic oscillations of the solidification of pure Al has a significant refinement. With
A magnetic field strength, with the current intensity increases, the grain size small. At the same current intensity, the grain refinement of the magnetic field strength
Increased first increases and then decreases, when the current is 10A, the magnetic field strength in the presence of 6T at the best value for refinement. (2) Al-6wt% Si
Solidification process and the AC magnetic field at the same time, dramatically reduce the grain size, dendritic morphology changed from the rose-shaped. Magnetic
Field is constant, when the magnetic field intensity is small (less than 4T), the grain size increases with increasing current density; magnetic field strength greater than 4T, the crystal
Basic grain size does not change with the current density; a certain current density, the grain size as the magnetic field strength increases. Electromagnetic oscillations
Not only to refine the α-Al, and can refine the eutectic silicon, the eutectic from the thick plate-like needles into small flakes.
(3) in the Al-12.6wt% Si eutectic alloy solidification process to impose a single strong magnetic field, eutectic refinement. Steady magnetic applied while
Alternating electromagnetic field and vibration. When the oscillator strength is small, coarse eutectic structure; when the oscillation reaches a certain intensity, the occurrence of divorce
Crystal, the formation of α-Al, eutectic silicon grains and primary silicon three kinds of co-existence of a special organization. (4) Al-18wt% Si hypereutectic alloy condensate
Solid process to impose a single strong magnetic field, with the magnetic field strength increases, the primary silicon refinement. Steady applied while producing a strong magnetic field and AC
Health and electromagnetic oscillations, with the oscillation increases, the primary silicon through collisions, reunion, dispersion and migration process, and ultimately the formation of uniform refinement of the group
Organization. Through the analysis of alloy solidification curve and found that the increased role of the electromagnetic composite of primary silicon nucleation temperature, reducing the nucleation undercooling,
The growth of primary silicon extended time. Oscillation mode to promote the growth of primary silicon growth by the continuous growth into a layered, but also by the bulky form
Flake into a small five-star block. Based on the above electromagnetic oscillations of the alloy solidification, based on impact studies, carry out mining
Applied with the local electromagnetic oscillations to study the complex field of fine-grained range of impact studies. The results showed that: the same magnetic field intensity, current strength, the
Large, detailed effects of the greater transmission range. The same current intensity, the grain refinement of the range increases with the magnetic field first increases and then decreases slightly
, There is extreme. Field analysis of that complex is due to grain refinement of oscillation from the nucleation sites to promote nucleation, the formation of free crystal, travel
From the crystal under the sink in the role of external forces to form a "crystal rain", which led to fine-grained changes in the scope. Use by primary nuclei in a magnetic field
Magnetic force principle, the use of strong magnetic field gradient control "crystal rain" method. And the establishment of a strong magnetic field gradient in spherical metal melt
Dynamic model of particle migration in general, the model was solved to get the gradient magnetic field particle velocity analytical solution:
To further study the combined effects of electromagnetic influence on metal solidification process, the use of EBSD study of the electromagnetic oscillations of the aluminum grain boundary structure
Impact. Found that oscillations can change the aluminum grain boundary structure, so that small angle grain boundaries increased, thereby enhancing the material's resistance to corrosion. Profit
With the Al-4.5% Cu alloy investigated the electromagnetic oscillations of the alloy orientation. X-ray diffraction results showed that: composite applied field, the grain
<111> crystal orientation to the direction along the magnetic field; degree of grain orientation with grain refinement with increasing trend. Spin orientation from the spherical particles and particle migration
Derivation of the crystal size and angle of orientation relationships. Finally, the electromagnetic field in a composite, based on experimental studies,
Proposed a composite AC EMC electromagnetic continuous casting of new technology and the success of this process in industrial experiments. Through experiments on brass
Show that: composite AC technology can improve the EMC slab surface and internal quality, improve the mechanical properties of the slab. Then the electromagnetic re-
Co-field technology in welding process. The use of magnetic mirror principle, the design of complex electromagnetic field oscillations under the TIG welding process. Experiments show that:
The device generates a magnetic field can effectively control the arc rotation frequency and arc shape, and thus have a significant impact on TIG welding process, fine
Of grain, improve weld performance. Degree Year: 2009