Study On The Physical Properties Of Fe-Ga Magnetostrictive Alloy

As a new type of magnetostrictive material, Fe-Ga alloy is another important finding in magnetorictive field yet after Tb-Dy-Fe alloy in recent years.In this thesis, the phase structure and magnetostriction of Fe-Ga alloys have been researched, in order to find out the relationship between microstructure, process methods, properties, try to improve some of its application cha-racteristics and find out the new Fe-based magnetostrictive materials. The microdefects, magnetic magnetization curves and electric characters of Fe(100-x)Gax(x=16,17,18,19,20),Fe82Ga(18-x)Mnx(x=3,5,7,9) and Fe82Ga(18-x)Alx (x=3,5,7,9) had been studied in the paper. The experimental results as follows:(1) The X-ray diffraction patterns show that the Fe100-xGax alloys is similar to that of α-Fe, which keeps the original structure of BCC. Ga atoms occupied the positions of (110) at first, the magnetostrictive coefficient of alloy increases with the adding of the Ga, when the percentage of Ga is 18, magnetostrictive coefficient is the maximum occurs, and when the percentage of Ga is more than 18, it began to occupied the positions of (200), the magnetostrictive coefficient of alloy decreases with the adding of the Ga atoms.The alloy lattice structure has been destructed with the inserting of Ga atoms, with the increasing of Ga atoms, some small vacancies combined to larger free volume; the defects in the alloys can pin the domain. The appropriate density of the defects can improve the saturated magnetization of Fe-Ga alloys. As the percentage of Ga is 18, the Lattice spacing made up to 2.8856 A, the saturated magnetization is the maximum occurs, it is 177.4Am2/kg, the magnetostrictive coefficient can make up to 47.08ppm; the magnetic field to get the saturated magnetization is least, it is 5106Oe. With increasing the Ga content, the Vickers-hardness shows no obvious rule, but in a generally increasing trend. The Ga content within 20at%, the Vickers-hardness in the alloy changed little, but increased significantly as Ga content up to 20at%.(2) The adding of Mn did not change the basic structure of the alloy which keeps the original structure. With the adding of Mn atoms, some small vacancies increased and the larger free volume decreased, the saturated magnetization, Vickers-hardness, the magnetostrictive coefficient reduced more. As the percentage of Mn is 9, the saturated magnetization decreased rapidly, it is 123.28Am2/kg. As the percentage of Mn is 5, the Vickers-hardness is least, it is 216.5kgf/mm; the magnetostrictive coefficient is 27.11ppm, which is the minimum occurs.(3) The adding of Al did not change the basic structure of the alloy which keeps the original structure. With the adding of Al atoms, some small vacancies combined to larger free volume, and it has little influences on the saturated magnetization, but it made the Vickers-hardness and the magnetostrictive coefficient reduced more. As the percentage of A1 is 3, the saturated magnetization made up to 198.86Am2/kg, the magnetostrictive coefficient is the minimum occurs, it is 13.79ppm. As the percentage of Al is 7, the Vickers-hardness is the minimum occurs, it is 230.2kgf7mm2.