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An interatomic potential is constructed for the ternary Al-Mg-Zn system under a proposed modified tight-binding scheme, and it is verified to be realistic. Applying this ternary potential, atomistic simulations predict an intrinsic glass formation region in the composition triangle, within which the glassy alloys are more energetically favored in comparison with their solid solution counterparts. Kinetically, the amorphization driving force of each disordered state is derived to correlate the readiness of its glass-forming ability in practice; thus, an optimal stoichiometry region is pinpointed around Al35Mg35Zn30. Furthermore, by monitoring the structural evolution for various (Al50Mg50)1−xZnx (x = 30, 50, and 70 at.%) compositions, the optimized-glass-former Al35Mg35Zn30 is characterized by both the highest degree of icosahedral ordering and the highest phase stability among the investigated compositions. In addition, the icosahedral network in Al35Mg35Zn30 exhibits a much higher cross-linking degree than that in Al25Mg25Zn50. This suggests that there is a certain correlation between the icosahedral ordering and the larger glass-forming ability of Al35Mg35Zn30. Our results have significant implications in clarifying glass formation and hierarchical atomic structures, and in designing new ternary Al-Mg-Zn glassy alloys with high GFA.

In this work, a rapid and controllable ultrasonic vibration method for forming Al-based metallic glass at room temperature is proposed. This method can dramatically improve the forming ability of Al-based metallic glasses, which are virtually brittle at room temperature and have almost no supercooled liquid region at high temperatures. Under ultrasonic vibration, Al-based metallic glasses exhibited obvious plastic flow, with a maximum deformation degree up to 58% and an average deformation degree up to 43%. It is worth mentioning that no crystalline peaks were found on the X-ray diffraction patterns after deformation under ultrasonic vibration, and the mechanical properties remained the same as the primary sample. The present results provide a new approach for the deformation and forming of Al-based metallic glasses, which can significantly broaden their applications.

In this work, magnetocaloric and magnetoresistance properties of Fe-based (Fe 0.402 Co 0.201 Ni 0.067 B 0.227 Si 0.053 Nb 0.05 ) 100 - x Cu x (x = 0, 0.5, 0.75, 1) amorphous ribbons formed by melt-spinning method and the effect of Cu on these properties were investigated. Curie temperature ( T C ) was not changed with the addition of Cu up to 0.5% to the composition. On the other hand, for Fe-based (Fe 0.402 Co 0.201 Ni 0.067 B 0.227 Si 0.053 Nb 0.05 ) 100−x Cu x (x = 0.75 and 1), T C increased from 505 K (for x = 0.5) to 526 K (for x = 0.75) and almost remain constant for x = 1. Maximum magnetic entropy change (−Δ S M ) max and refrigeration capacity (RC) values were found to be in the range of 0.62–1.25 Jkg − 1 K − 1 and 62–158.75 Jkg − 1 respectively for (Fe 0.402 Co 0.201 Ni 0.067 B 0.227 Si 0.053 Nb 0.05 ) 100 − x Cu x (x = 0, 0.5, 0.75, 1) amorphous ribbons under a maximum field of 2 T. These values are comparable with those of previously studied Fe-based metallic glasses. In addition, the maximum temperature dependent magnetoresistance (MR (%)) values for (Fe 0.402 Co 0.201 Ni 0.067 B 0.227 Si 0.053 Nb 0.05 ) 100 − x Cu x (x = 0, 0.5, 0.75, 1) were found to be 125, 17, 7, and 1% around the Curie temperatures under an applied field of 1 T, respectively. The magnetoresistance values of Cu-free Fe-based glassy alloy are higher than those of Cu-doped alloys. The results show that appropriate amount of Cu substitution (x = 0.75, 1) can enhance the RC and (−Δ S M ) max . The suitable RC, large magnetoresistance, good thermal stability, and negligible hysteresis offer that these Fe-based glassy alloys exhibit promising applications as high-temperature magnetic refrigerants and multi-functional materials working in the temperature range of 400–600 K.

WOS:000393819100002 In this work, Co-based (Co0.402Fe0.201Ni0.067B0.227Si0.053Nb0.05)(100-x) Cu-x bulk glassy alloys (BMG) with 2 mm diameters were formed by suctioncasting method and effect of Cu in this system's thermal stability, glass forming ability and magnetic properties were also investigated. The curves of thermal analysis, obtained using differential scanning calorimetry, show that (Co0.402Fe0.201Ni0.067 B0.227Si0.053Nb0.05)(100-x) Cu-x (x = 0-2) has supercooled liquid region (Delta T-x) of about 45 K, and reduced glass transition temperature (T-g/T-l) lies in the range from 0.663 to 0.678. The saturation magnetisation (J(s)) and coercivity (H-c) for ascast BMG were in the range of 0.46 T-0.65 T and 13 A/m, respectively. Commission of Scientific Research Projects of Uludag UniversityUludag University [KUAP(F)-2015/50, KUAP(F)-2013/25] This work was partially supported by the Commission of Scientific Research Projects of Uludag University [Project number KUAP(F)-2015/50], [Project number KUAP(F)-2013/25].

The magnetocaloric and magnetoresistance properties of amorphous Co-based (Co0.402Fe0.201Ni0.067B0.227Si0.053Nb0.05)(100-x)Cu-x (x=0, 0.5, 0.75 and 1) ribbons were investigated. Cu additions changed the crystallisation temperature (T-x) and the Curie temperature (T-C). The saturation magnetisation (M-s) and coercivity (H-c) for alloys were in the range of 65.51-38.49 emu/g and 1.99-6.84 A/m, respectively. Under an applied magnetic field change of 2.2 T, the (-S-M)(max) for (Co0.402Fe0.201Ni0.067B0.227Si0.053Nb0.05)(100-x)Cu-x with x=0, 0.5, 0.75 and 1 are 0.77, 0.71, 0.89 and 0.67 Jkg(-1)K(-1), respectively. The values of refrigeration capacity (RC) for the as-spun glassy alloys are comparable with those of previously studied Fe-based metallic glasses such as Fe80B10Zr9Cu1, (Fe0.76B0.24)(96)Nb-4 and Fe82Ni2Zr6B10. In addition, the maximum magnetoresistance (MR) values for (Co0.402Fe0.201Ni0.067B0.227Si0.053Nb0.05)(100-x)Cu-x with x=0, 0.5, 0.75 and 1 are found to be 110, 38, 23 and 1% around the Curie temperatures under an applied magnetic field change of 1 T, respectively. With good RC, negligible hysteresis due to very low coercivity values and large magnetoresistance, these Co-based amorphous alloys can be used as the high temperature magnetic refrigerants and multifunctional applications working in the temperature range of 450-600K.

A new Fe-based bulk metallic glass with superior glass-forming ability (GFA), Fe46Cr15Mo14C15B6Nb4, was developed based on the Fe-Cr-Mo-C-B alloy system by minor addition of Nb. The effects of Nb addition on glass formation of the Fe-50 xCr15Mo14C15B6Nbx (x = 0, 2, 4 and 6 at.%) alloys were investigated. The optimum addition content of Nb was determined as 4 at.% by X-ray diffraction and differential scanning calorimeter analysis. A fully amorphous rod sample with 3 mm in diameter was produced by using commercial-grade raw materials and a copper mold casting technique. This alloy shows an ultimate compressive strength of 1920 MPa and Vicker's hardness 1360 H-V, which is two to three times that of conventional high strength steel and suggests a promising potential for applications combining outstanding corrosion and wear resistance properties. The crystallization kinetics studies found that the activation energies for glass transition, onset of crystallization and crystallization peak were higher than those of other reported Fe-based bulk metallic glasses. The value of the fragility parameter m for the Fe46Cr15Mo14C15B6Nb4 alloy was calculated to be 34, indicating that the Fe-Cr-Mo-C-B-Nb alloy system is a strong glass former according to the Angell's classification scheme. It is inferred that the more sequential change in the atomic size, the generation of new atomic pairs with large negative heats of mixing and the amount of oxygen in the molten liquid neutralized into Nb oxides provide a synergetic effect for the remarkably improved GFA and thermal stability. (C) 2014 Elsevier B.V. All rights reserved.

The effect of low amounts of Cr on glass forming ability and corrosion behavior of Fe(65-x)CrxMo14C15B6 (x = 0, 2, 4, 6, 8,10 at.%) ribbons have been studied. It was found that the reduced glass transition temperature (T-rg) do not change significantly with Cr content. The glass forming ability (GFA) of this system is evaluated by the gamma(m), delta and omega parameters and the alloys containing 4 and 6 at.% were found to be the best glass formers in this system. The temperature interval of the supercooled liquid region (Delta T-x) changed with Cr and was enlarged from 35 K at x = 0 to 50 K at x = 4. Corrosion rates measured by immersion tests in H2SO4 decreased with an increase of chromium content in the alloys. The electrochemical measurements indicate that the alloys containing more than 4 at.% of Cr are spontaneously passivated with low current densities in 0.1 N H2SO4 whereas the alloys with Cr content

Bulk Metallic Glasses (BMG) are metallic alloys that have the ability to solidify in an amorphous state. BMGs show enhanced properties, for instance, high hardness, strength, and excellent corrosion and wear resistance. BMGs produced by conventional methods are limited in size due to the high cooling rates required to avoid crystallization and the associated detrimental mechanical properties. Additive manufacturing (AM) techniques are a potential solution to this problem as the interaction between the heat source, e.g., laser, and the feedstock, e.g., powder, is short and confined to a small volume. However, producing amorphous parts with AM techniques with mechanical properties comparable to as-cast samples remains a challenge for most BMGs, and a complete understanding of the crystallization mechanisms is missing. This review paper tries to cover recent progress in this field and develop a thorough understanding of the correlation between different aspects of the topic. The following subjects are addressed: (i) AM techniques used for the fabrication of BMGs, (ii) particular BMGs used in AM, (iii) specific challenges in AM of BMGs such as the control of defects and crystallization, (iv) process optimization of mechanical properties, and (v) future trends.