The effect of Ni-substitution on physical Properties of Fe 72-x B 24 Nb 4 Ni x Bulk Metallic Glassy Alloys
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The effect of Ni-substitution on physical Properties of Fe72-xB24Nb4Nix Bulk Metallic Glassy Alloys Ansar Masood, Anis Biswas, V.Ström, L. Belova, J. Ågren and K. V. Rao Department of Materials Science-Tmfy-MSE, the Royal Institute of Technology, S- 100 44, Stockholm, Sweden
ABSTRACT We have succeeded in producing bulk metallic glass by partial substitution of Fe with Ni in Fe-B-Nb alloys which could otherwise be only melt spun into amorphous ribbons. Substitution by Ni in the Fe72-xB24Nb4Nix alloys with (x ~2, 4, 6, 8, 10, 12 and 14) improves the glass forming ability of the materials and as a result rods of same compositions can be fabricated. Magnetically the BMG alloys remain soft with coercitivities below 500 mOeHowever, the electrical resistivity of the system decreases significantly by as much as a factor of two with the increase of Ni concentration, and becomes more metallic like with a positive temperature coefficient. INTRODUCTION It is well known that although multicomponent Fe based amorphous ribbons can be mult spun it is not obvious that for the same composition we can obtain Bulk metallic glasses (BMG). Methods to enhanced of the glass forming ability to obtain BMGs of the same composition is thus a topic attracting considerable attention from both fundamental as well as the application point of view [1–12]. The kinetics of phase transformation along with the growth mechanism of glass formation is an intriguing subject for the fundamental studies [13, 14]. Since BMG materials often have exceptional mechanical strength, corrosion resistance and excellent soft magnetic properties they are plausible candidates for a variety of electrical and electronic component development [1–12]. One important objective is to develop BMG materials with larger cross sections without losing their excellent properties of the glassy state. The ability to fabricate BMGs with larger cross section for a BMG is closely related to its glass forming ability (GFA). In this regard, Inoue put forward three empirical rules [4] for better stabilization of the glassy state: (a) the alloys should have at least three constituent atoms. (b) the atomic size difference between component elements must be greater than 12% and (c) the constituent elements must have large negative heat of mixing. These criteria have led to the synthesis of a large number of BMGs with cross sections from a few mm to even few tens of mm. However, despite following Inoue’s rules, why some alloys can easily be cast into BMG while others can not is not well understood. Fe-based BMGs are particularly interesting because they show almost square hysteretic loops with quite large saturation magnetization and rather small coercivity [8, 11]. Generally Febased alloys have low GFA and poor thermal stability, which are disadvantageous to produce BMGs [8]. This work is an investigation on determining how the properties of a Fe-based system modified on partial substitution of Fe with Ni. We have prepared alloys of Fe72xB24Nb4Nix (x ~2, 4, 6, 8, 10, 12 and 14) and studied th
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