Metallic Glass Strips Research Articles

A Multiple Twin-Roller Casting Technique for Producing Metallic Glass and Metallic Glass Composite Strips.

To date it has not been possible to produce metallic glass strips with a thickness larger than 150 μm via single-roller melt spinning technique, and it remains challenging to produce thick metallic glass strips. In this work, a multiple twin-roller casting technique is proposed for producing thick metallic glass and metallic glass composite strips. A triple twin-roller casting device, as a specific case of the multiple twin-roller, was designed and manufactured. The triple twin-roller device possesses a high cooling rate and involves a long contact time between the melt and the strip, which makes it an efficient technique for producing metallic glass strips that avoids crystallization, although the solidification temperature ranges of metallic glasses are as wide as several hundred Kelvins. The two prepared metallic glass (MG) strips are in a fully amorphous state, and the MG strip shows excellent capacity of stored elastic energy under 3-point bending. Furthermore, the Ti-based metallic glass composite strip produced via the triple twin-roller casting exhibits a novel microstructure with much finer and more homogenously orientated β-Ti crystals, as compared with the microstructure of metallic glass composites produced by the common copper mold casting technique.

Rejuvenated metallic glass strips produced via twin-roll casting

The energy state and atomic level structure of metallic glasses (MGs) are very sensitive to their cooling rates, and a lower cooling rate generally causes a lower energy and more relaxed state of MGs. In this work, the Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit. 1) ribbons with a thickness of 40 μm and 110 μm and the strips with a thickness of 320 μm and 490 μm were produced by single-roll melt spinning and twin-roll casting, respectively. The increase in thickness of either ribbons or strips results in a lower energy state with a smaller relaxation enthalpy, a lower content of free volume, and a higher hardness. Although the cooling rate of the twin-roll produced 320 μm-thick strip is almost one magnitude lower than that of the single-roll produced 110 μm-thick ribbon, the former, however, possesses a rejuvenated energy state as compared to the latter. Molecular dynamics simulations reveal that the squeezing force during twin-roll casting affects the evolution of connection types of clusters, and the 2-atom and 4-atom connections are prone to be retained, which results in a higher energy state of MGs. Such a rejuvenation process during twin-roll casting can overwhelm the relaxation process caused by the lower cooling rate. Therefore, twin-roll casting is not only a method being capable for producing strips with a large thickness, but also prone to obtain a high energy state of the MG strip.

Magnetostriction hysteresis loops of annealed Fe73.5Cu1Nb3Si15.5B7 metallic glass strips

Magnetostriction hysteresis loops of Fe73.5Cu1Nb3Si15.5B7 metallic glass strips annealed in vacuum for 1 h at temperatures ranging from 300 to 650°C were determined using a strain-gauge method. The magnetostriction at Hm = 2.8–3.0 kA/m decreased from 25 × 10−6 after annealing at 300°C to 21 × 10−6 after annealing at 560°C, to about 2 × 10−6 after annealing at 600°C, and increased to approximately 6 × 10−6 after annealing at 650°C. The remanent magnetostriction after annealing from 300 to 560°C increased from 1.35 × 10−6 to 5.01 × 10−6.

Demonstration of a fiber optic array of three-axis magnetometers for undersea application

We describe an undersea array of eight fiber-optic, three-axis magnetic sensors. The interferometric sensors employ magnetostrictive metallic glass strips as the transducer elements. We discuss the operating principles and the performance of the system during actual undersea operation.

Moduli of elasticity of Fe/sub 80/B/sub 12/Si/sub 8/ metallic glass strips annealed in vacuum at 370 and 380°C

Elasticity moduli at constant magnetic field and at constant induction as the functions of magnetic bias field of the strips of Fe/sub 20/B/sub 12/Si/sub 8/ metallic glass annealed in vacuum at temperatures of 370 and 380/spl deg/C were investigated. The values of moduli in as-quenched state were changing from 133 to 155 GPa. After annealing at 370/spl deg/C the moduli changes were from 80 to 170 GPa and after heat treatment at 380/spl deg/C /spl Delta/E effect increased and these changes were from 60 to 170 GPa. >

Consolidation of Ni60Nb40 Metallic Glass Strips into Metal Matrix Composites

ABSTRACTTo fully utilize the promising mechanical properties of metallic glasses, consolidation techniques need to be developed to incorporate them into large bulk forms. This paper describes preliminary results on the consolidation of Ni60Nb40 metallic glass strips into an aluminum alloy matrix. The consolidation was achieved without the degradation of the metallic glass by employing a superplastic aluminum alloy as the matrix material. The consolidations were accomplished at a superplastic forming temperature compatible with the metal matrix material and sufficiently below the critical 650°C crystallization temperature of the Ni60Nb40 metallic glass. Initial studies employed an atuminum − 5% calcium − 5% zinc alloy as the metal matrix material.

Low-field magnetic properties of wide Fe-Ni metallic glass strips

Wide samples of continuous-cast metallic glass ribbons fabricated to tape-wound or punched-ring core configurations are shown to possess the same attractive low-field magnetic properties as are observed in narrow ribbons of similar composition. Annealing ring-laminated cores in crossed fields leads to lower core loss than for metallic glass (wide or narrow) annealed only in a circumferential field.