| Fe alloys with nonmagnetic elements in which there are no d-shell electrons(Al) or the d-shell is full(Ga),are known to have appreciable low field magnetostriction,good mechanical properties,low magneto-crystalline anisotropy and relatively low cost.Therefore,the new magnetostrictive materials,Fe based alloys can be widely applied in the actuator.In this paper, Fe-Ga-Al magnetostrictive materials and the application in the actuator has been researched,as follows.The 21 ingots were prepared from high purity elements using a high vacuum arc melting system.The isothermal section at 650℃and the vertical section Fe-(Ga0.75Al0.25) of the Fe-rich portion in the Fe-Ga-Al ternary system were determined using optical microscopy,scanning electron microscopy,energy dispersion X-ray spectroscopy,X-ray diffraction and differential thermal analysis.It was found that the A2 phase region remains almost unchanged with increasing Al content.However,the D019 single-phase region rapidly reduces when a small amount of Al is substituted for Ga in Fe-Ga alloys.Compared to the Fe-Ga binary phase diagram, the A2 and L12 single-phase regions move toward the right of the vertical section,and the D019 single-phase region disappears.According to the results of the research and the magnetostriction theories,the area of the optimization composition has been forecasted.Fe82Ga18-xAlx(3≤x≤13.5) alloys has been researched.It was found that the magnetostriction value of the e82Ga9Al9 alloy increased from 88×10-6 before magnetic heat treatment to 114×10-6 after magnetic heat treatment.Up to now,the magnetostriction is the highest value of the alloys using the arc melting.The directional solidification Fe82Ga9Al9 alloy was prepared using a directional solidification furnace.We measured the magnetostriction under compressive stresses ranging.Tests showed that the magnetostriction increased from 135ppm to 221ppm with the increasing value(0-53MPa) of compressive stresses.And the magetostriction is higher than the value in the N.Srisukhumbowornchai's study.The new magnetostrictive actuator has been designed and made with the directional solidification Fe82Ga9Al9 alloy rod,which based on designing magnetic circuit,the water-cooling system and the pre-stress mechanism.The investigation to the Fe-Ga-Al magnetostrictive actuator indicates its output displacement has good linearity.Comparing with Terfenol-D giant magnetostrictive actuator,the Fe-Ga-Almagnetostrictive actuator has better precision.Including the DC magnetic field,the vacuum system and the heating system,the magnetic field heat treatment furnace has been designed and made.The furnace chamber can be vacuumized in this equipment,which will simplify magnetic field heat treatment.Measuring and controlling of temperature in the furnace chamber will be more accurate by using double temperature controllers.The furnace has high magnetic field(Hmax=3 kOe) and temperature (Tmax=800℃),meanwhile,its size is not too large.The two actual applications,indicating the function of the furnace is fine,was listed.
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