Studies in Metallurgical and Magnetic Properties of Permalloys for Industrial Applications

Abstract

Permalloys in which Ni-Fe systems largely dominate, have found usage in many electrical /electronics consumable goods. The subject is vast enough to spell out all useful applications therefore we have focused our work aiming at the recording head and watch component materials. This is due to the fact that these devices consume large amounts of such alloys.The work carried out in the thesis comprises of the study of the influence of various processing parameters such as annealing temperature, holding time and cooling rate under hydrogen atmosphere on the magnetic properties of the Ni-Fe alloys. The three samples adopted for the present investigation includes 82.13 % Ni (sample A), 79.90 % Ni (sample B) and 47.01 % Ni (sample C). The materials were characterised for their chemical composition by wet chemical analysis and atomic absorption spectrometer. The first step involved was the preparation of ring samples. Die and punch was designed and fabricated especially to punch the ring of desired shape and size. To anneal the samples in hydrogen atmosphere one lab model hydrogen annealing furnace was designed and developed upto measuring temperature range of 1200C. The samples prepared under different conditions were analysed with optical microscope and X-ray diffractograph (XRD). The magnetic properties were studied with a standard B-H analyser. The prepared samples were tested for industrial applications such as watch and audio recording applications. We compared the performance of the material/device developed through the proposed route with the existing ones by checking the electro-mechanical characteristics of watch movement and also audio recording characteristics of audio head.