Effect of heat treatment on structure and magnetic properties of Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk amorphous alloy

Abstract

T he development of empirical rules for the synthesis of bulk metallic glasses and methods for the evaluation of increased affinity to amorphization has enabled the production of alloys with a significantly reduced critical cooling rate of several hundred K·s -1 and increased maximum casting dimensions of about 5-6 mm which generate an amorphous structure [1][2][3] .Abstract: This study deals with the Fe 65.5 Cr 4 Mo 4 Ga 4 P 12 C 5 B 5.5 ferromagnetic bulk amorphous alloy. XRD analysisshowed an amorphous structure of the as-cast sample. The same method revealed that, after annealing at 973 K for τ=10 min, the sample displayed a crystalline structure with crystalline phases formed. The crystallization process of the alloy was examined by DTA analysis. It was shown that crystallization took place in the temperature range between 810 K and 860 K with the exo-maximum peak temperature at 846 K with a heating rate of 20 K·min -1 . The method also showed that, at temperatures ranging from 753 K to 810 K, the alloy exhibited the properties of supercooled liquids. A correlation between heat-induced structural changes and magnetic properties of the alloy was determined by thermomagnetic measurements. Maximum magnetization M=3.7 Am 2 ·kg -1 of the alloy was reached after its annealing at 733 K for τ=10 min. Upon annealing, the alloy exhibited a relaxed amorphous structure. Annealing the alloy above the crystallization temperature led to a decrease in bulk magnetization. After annealing at 973 K for τ=10 min, the bulk magnetization of the alloy was M'=0.45 Am . Accordingly, after crystallization and formation of new compounds, the magnetization of the alloy was decreased by a factor of about 7.7. The strength of the magnetic field applied during the measurements was H=10 kA·m -1 . The samples were tested for changes in the microstructure and hardness of both the amorphous phase and the resulting crystalline phase.

Glass formation in Fe-Cr-Zr-B-Mo alloys by tuning Nb addition

“…

Fe-based bulk metallic glasses (BMGs) have become the focus of scientific research due to their good soft magnetic properties, excellent mechanical properties, outstanding corrosion resistance, biocompatibility and low material cost [1][2][3][4] . In 1995, the first Fe-based BMG with a dimension of millimeters was developed in Fe-Al-Ga-P-C-B system [5] .

…”