Effect of minor Fe addition on glass forming ability and mechanical properties of Zr_(55)Al_(10)Ni_5Cu_(30) bulk metallic glass

A series of rod samples with diameter of 3 mm（Zr0.55Al0.10Ni0.05Cu0.30）100-xFex（x=0,1,2,3,4） were prepared by magnetic suspend melting and copper mold suction casting method.The effects of a small amount of Fe on glass forming ability（GFA） and mechanical properties of Zr55Al10Ni5Cu30 bulk metallic glass（BMG） were investigated.The results show that the addition of an appropriate amount（less than 3%,mole fraction） of Fe enhances GFA,as indicated by the increase in the reduced glass transition temperature Trg（=Tg/Tl） and the parameter γ（=Tx/（Tg＋Tl）） with increasing Fe content,and GFA gets deteriorated by further Fe addition（4%）.The addition of Fe also effectively improves the compressive plasticity and increases the compressive fracture strength in these Zr-based BMGs.Compressive tests on BMG sample with 3 mm in diameter and 6 mm in length reveal work-hardening and a certain plastic strain in the alloy containing 2% Fe.The BMG composite containing 4% Fe also exhibits a high fracture strength along with significant plasticity.

Design of high strength Fe-(P,C)-based bulk metallic glasses with Nb addition

Bulk metallic glass（BMG） rods Fe71Mo5-xNbxP12C10B2（x=1,2,3,4 and 5） with diameter of 1 or 2 mm were synthesized by copper mold casting.The effects of Nb substitution for Mo on the structure,thermal and mechanical properties of Fe71Mo5-xNbxP12C10B2 alloys were studied by X-ray diffraction,differential scanning calorimetry and compressive testing.The results show that the substitution of Nb for Mo leads to a decreased glass forming ability,but with plasticity of 1.0%,the fracture strength of Fe71Mo2Nb3P12C10B2 alloy increases up to 4.0 GPa.The improvement of the fracture strength is discussed in terms of the enhancement of atomic bonding nature and the favorite formation of a network-like structure due to the substitution of Nb for Mo.

Amorphous-crystalline transition layers formation during quenching of Fe_(61)Co_7Zr_(10)Mo_5W_2B_(15) melt

New Fe-based multicomponent amorphous alloys have been developed recently based on empirical rules for large glass forming ability(GFA). In the present investigation, the master alloy ingot with the nominal composition of Fe 61Co 7Zr 10Mo 5W 2B 15(mole fraction, %) was prepared by arc-melting under Ti-gettered Ar atmosphere. The Fe-based buttons with different transverse cross sections were fabricated by arc-melting method, and the d 2.5 mm Fe-based rods were manufactured by injection technique. Characterization of the ingots and the parameters associated with the thermal stability were carried out by X-ray diffractometry(XRD) and high temperature differential scanning calorimeter(DSC), respectively. The interval of the supercooled liquid region is 39 K for the Fe-based alloy. The GFA of Fe-based alloys is relatively lower, to the buttons obtained are all crystallized. The Fe-based rod exhibites a high Vickers hardness up to HV 1 329. In addition, an amorphous-crystalline transition layers are observed in the rod. This transition zone is caused by unhomogeneous temperature distribution and relatively lower GFA for Fe-based alloys.

Zr-Co(Cu)-Al bulk metallic glasses with optimal glass-forming ability and their compressive properties

The formation of bulk metallic glasses（BMGs） in the ternary Zr（56） Co（28-x）Al（16） and quaternary Zr（56） Co（28-x）CuxAl16（x=2, 4, 5, 6, 7, mole fraction, %） glassy alloys was investigated via the copper mold suction casting method. The main purpose of this work was to locate the optimal BMG-forming composition for the quaternary Zr Co（Cu）Al alloys and to improve the plasticity of the parent alloy. The X-ray diffractometry（XRD）, transmission electron microscopy（TEM） and differential scanning calorimetry（DSC） were used to investigate the glassy alloys structure and their glass forming ability（GFA）. In addition, the compression test, microhardness, nano-indentation and scanning electron microscopy（SEM） were utilized to discuss the possible mechanisms involved in the enhanced plasticity achievement. The highest GFA among Cu-containing alloys was found for the Zr（56） Co（22） Cu6 Al（16） alloy, which was similar to that of the base alloy. Furthermore, the plasticity of the base alloy increased significantly from 3.3% to 6% for the Zr（56） Co（22） Cu）6 Al（16） BMG. The variations in the plasticity and GFA of the alloys were discussed by considering the positive heat of mixing within Cu and Co elements.

Glass formation and magnetic properties of Fe-based metallic glasses fabricated by low-purity industrial materials

Fe-based metallic glasses of(Fe74Nb6B20)100?xCrx(x=1,3,5)with high glass forming ability(GFA)and good magneticproperties were prepared using low-purity raw materials.Increasing Cr content does not significantly change glass transitiontemperature and onset crystallization temperature,while it enhances liquidus temperature.The addition of Cr improves the GFA ofthe(Fe74Nb6B20)100?xCrx glassy alloys compared to that in Cr-free Fe?Nb?B alloys,in which the supercooled liquid region(ΔTx),Trgandγare found to be50?54K,0.526?0.538,and0.367?0.371,respectively.The(Fe74Nb6B20)100?xCrx glassy alloys exhibit excellentsoft magnetic properties with high saturation magnetization of139?161A·m2/kg and low coercivity of30.24?58.9A/m.PresentFe?Nb?B?Cr glassy alloys exhibiting high GFA as well as excellent magnetic properties and low manufacturing cost make themsuitable for magnetic components for engineering application.

Glass formation,thermal and mechanical properties of ZrCuAlNi bulk metallic glasses

The glass forming ability, thermal and mechanical properties of some Zr Cu Al Ni bulk metallic glasses were analyzed. The compositions of the alloys were theoretically determined with the dense packing and kinetic fragility index models. Cylindrical and conical ingots were produced by copper mould suction-casting under Ar atmosphere. The conical ingots were characterized by means of X-ray diffraction in order to determine the glassy structure. It was found that both alloys have a critical glassy diameter, Dc, of 3 mm. Thermal behaviours were investigated by differential scanning calorimetry at heating rates of 0.5, 0.67 and 0.83 K/s. The gamma parameter γ, supercooled liquid region ΔTx, and reduced glass transition temperature Trg, of the experimentally obtained glasses indicated high glass forming ability. The glassy compositions showed a fragility index of ~40 GPa. The compression test of the investigated alloys was carried out at a strain rate of 0.016 s^-1, obtaining a elastic modulus of ~83 GPa, total deformation of ~5%, yield strength of 1.6 GPa and hardness of 4 GPa. It was concluded that the use of the dense packing and kinetic fragility index models helped to predict glass-forming compositions in the family alloy investigated.

Relationship of glass forming ability and local structural properties of liquid Cu-Zr alloys

Molecular dynamics(MD) simulations were performed to investigate the glass forming ability(GFA) and microscopic structural properties of liquid Cu-Zr alloys.Based on the analysis of composition dependences of the reduced glass transition temperatures and the excess volume,we found that the Cu-Zr glasses have the largest GFA at Cu65Zr35 composition.To get more detailed information of local structure,we calculated the pair correlation functions,partial pair correlation functions,the excess entropy,chemical order parameter,coordination number,and Voronoi index of Cu-Zr liquids.We found that there exists an obvious and close relationship among the GFA,the excess entropy calculated using the total pair correlation functions,chemical order parameters,and some Cu centered cluster with Voronoi index <0,2,8,1> and Zr centered cluster with Voronoi index <0,3,6,4>,which all have nonlinear dependences on Cu/Zr concentration and have extreme values at liquid Cu65Zr35 composition.

Development of soft magnetic amorphous alloys with distinctly high Fe content

This paper reports on the preparation of Fe82.7-85.7Si2-4.9B9.2-11.2P1.5.2.7C0,8 soft magnetic amorphous alloys with a distinctly high Fe content of 93.5-95.5 wt.% by component design and composition adjustment. All alloys can be readily fabricated into completely amorphous ribbon samples with good surface quality by the single copper roller melt-spinning method. These alloys show good bending ductility and excellent magnetic properties after annealing, i.e., low coercivity （He） of 3.3-5.9 A/m, high permeability （μe） of 5000-10000 and high flux saturation density （Bs） of 1.63-1.66 T. The mechanism of the good glass forming ability （GFA）and soft-magnetic properties are explored. The amorphous alloys with the high Fe content comparable to that of the desired high Si alloy can be promising candidates for the potential application in electric devices.