M¨ossbauer Study of Nanostructured γ-Ni-Fe Alloys Prepared by High Energy Ball Milling

Abstract

gamma-Ni-Fe alloys have attracted much attention because of their interesting magnetic properties and applicability to practical uses, such as recording head, transformers, or magnetic shielding materials. A Recent study showed that using a nono-processing technique in sample preparation can effectively improve the magnetic properties for applications. The Mechanochemical treatment method has some benefits,like preparing materials at room temperature, required neither melting nor colling of materials, and elaborating materials in the form of powder samples that are industrially useful for material forming. however, significant discrepancies in products and intrinsic properties of samples exist among the several processes used for sample preparation. In a previous work, nanostructured gamma-Ni-xFe alloys with a single crystal phase, which were synthesized by using a mechanochemical process and which had x= 30(S1), 45(S2), 55(S3), and 65(S4) wt% and an average grain size of 30 -40nm, were studied mainly for their macroscopic magnetic properties. The magnetic mesurements indicated that these nono-alloys showed no superparamagnetic phenomenon within the temperature ranges from 8.5K to 300K. Mossbauer spectroscopy is well Known to be useful for obtaining information about the microscopic nuclear environment affecting the physical properties of a system and for determining the magnetization in term of the magnetic field produced at the nuclei themselves without an externally applied field. The purpose of this study was to carry out Mossbauer measurement on the nanoparticles of previous samples to examine superparamagnetic properties of the samples and to obsreve the temperature dependent of the Mossbauer parameters of the samples.