Development Of The Temperature-magnetic Field Coupling Tester

The metal plasticity is a capability that the metal material has a permanentdeformation but its integrality can not be destroyed under the external force. Itis testified by the electron microscope, the micromechanism of the metal plasticdeformation is a harvmonious movement among the dislocations, twinborns,wrests in the grains and the grains.The previous papers have show that the electromagnetic field has an effecton the material such as metal and electrovalent compounds. However littleresearch has been done about the magnetic field effecting on the plasticity andsuperplasticity. During the research of the superconductive phenomenon, it wasfound that when the material change to superconductive state, the plasticity ofthe material will increase. Michel and other people think that this phenomenonrelates with the electronic subsystem in the dislocation dynamics.In fact, the effect of electric current on the plasticity is a compound effectincluding Joule's heat effect, the magnetic compress effect, and the electricplastic effect, besides, there may be the electric current skin effect and thethermoelectric effect. With the exception of the electric plastic effect, othereffect can be ignored by the appropriate experimental methods.The researches with regard to electric plastic effect, were be thoughtinitially that: when the electric pulse enter, there was a mutual effect betweenthe dislocations and the electrons which makes the dislocations disengage thetransfixion and slip, consequently the plastic deformations are easily continued.The further research show that: The 'electronic wind'make dislocation tangleunwrap and dislocations slip easily; sequentially the distribution of thedislocations become more uniform, the centralization of stress in thedeformations decrease, and finally the material's plasticity is increased.However, the subsequent researches show that: The 'electronic wind'is sosmall that can be ignored, and can not make the plasticity increase so muchunder the electronic current density which lead to electric plastic effect. Thenresearches for electric plastic effect are made in terms of magnetic field.Molotskii put forward a new matrix to parse the electric plastic effect. Thismatrix is: when the center of the transfixion, which block the movement of thedislocations, is paramagnetic phase, the inductive magnetic field caused by thepulse current have a large effect on the rate of the disengagement of thetransfixion. The calculations rooting in it show that the contributions that themagnetic field to the electric plastic effect is 104 order larger than the effect ofthe electric wind matrix. Because the matrix is based on the followingsuppositions: The all-important reason which causes the electric plastic effect isthe length increment of the uncontrolled section of the dislocations in themagnetic field, and the center of the transfixion is principally paramagnetic.Thus, the rationality of the matrix need to be studied further.Superplasticity is the common and potential property of the material whichhas the lattice structure. As far as the law of the macromechanics, the necking(i.e., geometry instability) will not appear after the load instability, It is possibleto rebuild the process of the quasi-stable deformation. In terms of themicrophysical process, superplastic deformation contain the complicatedprocess of the creep, the dislocation slide in the grain, the dislocation climbingalong the grain boundary, dynamic recovering and dynamic re-crystallization etal. In a word, superplasticity is a process that the steady deformation process isrebuilt after the deformation disability, and the microphysical process mostly isgrain boundary action such as grain boundary slide, migration and the grainshift. For the deformation mechanism of the superplasticity, there is not theuniversal mechanism mode at present. Some modes putted forward which canonly interpret one or several materials'superplastic phenomenon. Typicalmechanism modes include diffuse creep mechanism, dislocation creepmechanism, the grain boundary slide mechanism companying the diffuse creepor the dislocation creep mechanism, center-surface mechanism, grain rolling outmechanism. But from qualitative analysis, superplasticity also contain thecomplicated microcosmic process as above described. The investigation toElectro-superplasticity started only from 80 ages of last century, In abroad, It isConrad .et al., American people who chiefly investigate this phenomenon. Inour country, the study began latter, but some study is conducting now.In the investigation of basic theory, test instrument and research ideas aremost important, No advanced test instrument and study ideas, no advancedinvestigative achievement. It is so in the investigation of electromagnetic field'seffect on material plasticity and superplasticity. In some decades, the method oftest developed very fast, first, the electron beam irradiation, then applyingelectricity, finally, using the effect of the field. The test was carried out underlow temperature originally, it is under high temperature now. The researchthought is better and better.Based on the superplsaic uniaxial tensile analytic theory developed by mysupervisor, Prof. Song, the basic research of superplasticity mainly is the studyof parameters m, n and τ. So this paper, mainly study the effect of temperature,stable magnetic field, alternating field and coupling of them on parameters m, nand τ.For the test instrument about alternating electromagnetic field andtemperature coupling in my paper, the highest temperature is 800℃, making thespecimen in the strong alternating electromagnetic field during the superplasticdeformation at the same time. Alternating electromagnetic field is obtained byelectrifying loop, and the wave of alternating electromagnetic field ismodulated by that of the current in the electrifying loop, the magnitude of thecurrent in the loop controlling the intensity of the alternating electromagneticfield.This paper is a part of sperplastic research of Prof. Song and carried outbased on the integrated mode of 'Science, teaching and production'put forwardby Prof. Song. And this paper combine with the project 'New method forimproving the superplasticity of ceramics and comparative study with typicalsuperplastic materials'.There have been a lot of reports about research of electromagnetic field toplasticity and superplasticity of material, but, basically, the research stayed inthe qualitative level. There is not enough understanding of the effect mechanism,and the material which was investigated is limit. For further study, it's presentedin my paper that in the subsequent investigation, according to the professorSong'tensile theory of superplasticity, the quantitative investigation is carriedon.During the study on plasticity and superplasticity of material, observationalways starts from three levels, they are macroscopic level, optic microscopiclevel and electric microscopic level, which little concerns the level less thanatom, that is because people always consider the atom neutral, and the factorssuch as sample state, t experiment temperature, tensile speed, etc, have noinfluence on the polarity of the particles in material. However, the atom iscomposed of atomic nucleus with positive electricity and electrons withnegative electricity. Under the effects of strong eradiation, the outer electronsmay divorce from the atom because of bombardment. Besides, the atomicnucleus with positive electricity and the electrons with negative electricity may...