Synthesis and Magnetostrictive Properties of High-Pr Content  ${\rm Sm}_{1-x}{\rm Pr}_{x}{\rm Fe}_{1.9}$ Cubic Laves Alloys
Polycrystalline Sm<sub>1-</sub><i>x</i>Pr<i>x</i>Fe<sub>1.9</sub> (0.4 ≤ <i>x</i> ≤ 1.0) magnetostrictive alloys were synthesized by arc-melting and subsequent high-pressure annealing. Measurements of x-ray diffraction, magnetization, and magnetostriction were performed on the alloys. Due to the effects of high-pressure, the alloys are stabilized in cubic Laves phase with MgCu<sub>2</sub>-type structure. The Curie temperature of the cubic Laves phase decreases linearly with the increase of <i>x</i>, which can be associated with the decreasing strength of 3<i>d</i>-4<i>f</i> coupling. With increasing <i>x</i> , the anisotropy of the alloys first decreases to a minimum at <i>x</i> = 0.6 and then increases. The magnetostriction of Sm<sub>1-</sub><i>x</i>Pr<i>x</i>Fe<sub>1.9</sub> changes signs from negative into a positive at <i>x</i> = 0.6 . The saturation magnetostriction increases with increasing <i>x</i>, while the sample with <i>x</i> = 0.9 shows a peak at low magnetic fields.
Structure and magnetostriction of Sm1−xPrxFe2 and Sm0.9Pr0.1(Fe1−yBy)2 alloys
The structure, magnetostriction and anisotropy of Sm1-xPrxFe2 and Sm0.9Pr0.1(Fe1-yBy)(2) alloys have been investigated using X-ray diffraction, standard strain gauge technique and Mossbauer spectrum. It is found that the matrix of homogenized Sm1-xPrxFe2 alloys is the (Sm,Pr)Fe-2 phase with MgCu2-type cubic structure and the minor phases are (Sm,Pr)Fe-3 phase and rare earth-rich phase when x less than or equal to 0.3. When x = 0.4, the (Sm,Pr)Fe-3 phase is found to be the main phase and the minor phases become (Sm,Pr)Fe-2, (Sm,Pr)(2)Fe-17 and rare earth-rich phase. With further increasing Pr content, the amount of minor phases, (Sm,Pr)(2)Fe-17 and rare earth-rich phase increase, but that of (Sm,Pr)Fe-2 remains almost unchanged. For Sm0.9Pr0.1(Fe1-yBy)(2) alloys, the (Sm,Pr)(Fe,B)(2) as a matrix is up to y = 0.2, and the small amount of second phase is a rare earth-rich phase when y > 0.05. The manetostriction of Sm1-xPrxFe2 alloys exhibits a peak near x = 0.1 and that of Sm0.9Pr0.1(Fe1-yBy)(2) alloys decreases with increasing B content. The Mossbauer spectrum analysis shows that the easy axis of magnetization for Sm1-xPrxFe2 alloys lies in the direction up to x = 0.3 and the anisotropy of Sm1-xPrxFe2 alloys decreases with increasing Pr content. (C) 2002 Elsevier Science B.V. All rights reserved.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.