Ductile Fe-Based Bulk Metallic Glass with Good Soft-Magnetic Properties

Zhang, Tao; Liu, Fengjuan; Pang, Shujie; Li, Ran

doi:10.2320/matertrans.48.1157

Cited by 98 publications

(38 citation statements)

References 21 publications

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“…3, which is in good agreement with other reported BMGs [40][41][42]. that the fracture occurred in a brittle manner when the local critical shear stress was exceeded.…”

Section: Methodssupporting

confidence: 92%

Role of Nb in glass formation of Fe–Cr–Mo–C–B–Nb BMGs

Zhai

Pineda

Duarte

et al. 2014

Journal of Alloys and Compounds

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Abstract:A new Fe-based bulk metallic glass with superior glass forming ability, Fe 46 Cr 15 Mo 14 C 15 B 6 Nb 4 , was developed based on the Fe-Cr-Mo-C-B alloy system by minor addition of niobium. The effects of niobium addition on glass formation of the Fe 50-x Cr 15 Mo 14 C 15 B 6 Nb x (x=0, 2, 4 and 6 at.%) alloys were investigated. The optimum addition content of niobium 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 Vickers hardness 1360 HV, 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 Fe 46 Cr 15 Mo 14 C 15 B 6 Nb 4 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 2 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 niobium oxides provide a synergetic effect for the remarkably improved glass-forming ability and thermal stability.

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“…3, which is in good agreement with other reported BMGs [40][41][42]. that the fracture occurred in a brittle manner when the local critical shear stress was exceeded.…”

Section: Methodssupporting

confidence: 92%

Role of Nb in glass formation of Fe–Cr–Mo–C–B–Nb BMGs

Zhai

Pineda

Duarte

et al. 2014

Journal of Alloys and Compounds

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“…19 The stress intensity factor for the cylindrical configuration was evaluated using the analysis by Murakami. 20 Considering that the average ligament size in the present specimens was ϳ1 mm, and taking the yield strength for this family of glasses to be ϳ3200 MPa, 5,14,16,17 nominally plane strain conditions can be assumed for fracture toughness measurements of Ͻ60 MPa m 1/2 , as obtained here. Nevertheless, since sharp precracks ahead of the notches were not introduced in the present specimens the measured stress intensity factors are not standard K IC values.…”

mentioning

confidence: 99%

Glassy steel optimized for glass-forming ability and toughness

Demetriou¹,

Kaltenboeck²,

Suh³

et al. 2009

Applied Physics Letters

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An alloy development strategy coupled with toughness assessments and ultrasonic measurements is implemented to design a series of iron-based glass-forming alloys that demonstrate improved glass-forming ability and toughness. The combination of good glass-forming ability and high toughness demonstrated by the present alloys is uncommon in Fe-based systems, and is attributed to the ability of these compositions to form stable glass configurations associated with low activation barriers for shear flow, which tend to promote plastic flow and give rise to a toughness higher than other known Fe-based bulk-glass-forming systems. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3184792͔The remarkably high strength, modulus, and hardness of iron-based glasses, combined with their low cost, prompted an effort over the past five years to design amorphous steel suitable for structural applications. The development effort yielded glasses with critical rod diameters as large as 12 mm 1,2 and strengths in excess of 4 GPa. 3 These low-cost ultrastrong materials however exhibit fracture toughness values as low as 3 MPa m 1/2 , 4 well below acceptable toughness limits for structural materials. The low toughness has been linked to their elastic constants, specifically their high shear modulus, 5 which for some compositions exceeds 80 GPa. 3 Recent efforts to toughen these alloys by altering their composition yielded glasses with lower shear moduli ͑below 70 GPa͒, which exhibit improved notch toughness ͑as high as 50 MPa m 1/2 ͒ but compromised glass-forming ability ͑criti-cal rod diameters less than 3 mm͒. 5,6 In this study, we implement an alloy development strategy coupled with toughness assessment and ultrasonic measurements to design glassy steel alloys with particularly low shear moduli ͑below 60 GPa͒ that demonstrate high toughness ͑notch toughness in excess of 50 MPa m 1/2 ͒ yet adequate glass-forming ability ͑critical rod diameters as large as 6 mm͒.The link between the high shear modulus and the low toughness of Fe-based glasses rests on the argument that a high shear modulus implies a high resistance to relax stress by shear flow. In turn, this promotes cavitation and early fracture and thus limits toughness. Using a Frenkel-like analysis to study cooperative shearing, Johnson and Samwer 7 arrived at a quantitative expression for the activation energy for shear flow, that is, the energy barrier to initiate plastic flow. Specifically, a relationship was proposed between the shear-flow barrier W and the shear modulus G for a frozen-in atomic configuration at the glass transition temperature T g , given by W͑T g ͒ ϰ G͑T g ͒v m ͑T g ͒, 7 where v m is the molar volume, which usually varies little within an alloy family. Aside from their high G, the brittle behavior of these glasses can also be predicted by their high T g , which for some compositions exceeds 600°C. 1,2 The glass transition temperature is also a measure of W͑T g ͒, since the requirement for the liquid viscosity at T g ͑10 12 Pa s͒ gives W͑T g ͒Ϸ37RT g ....

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“…With Ni content, x, increasing from 0 to 11.1, the plastic strain increases from 2.2% to 4.0%, while the yield strength and fracture strength decrease from 3330 to 2780 MPa, and from 3400 to 3120 MPa, respectively, which implies that enhancing plasticity by adjusting the composition of alloys is followed with the loss of some strength. Similar to the Fe-Mo-P-C-B alloy system, 14) the large plasticity of present alloys attributes to high density of shear bands formed during compression. The fracture surface exhibits a typical vein pattern, which is the characteristic of ductile feature of BMGs.…”

Section: Resultsmentioning

confidence: 99%

“…13) Recently, we have reported Fe-Mo-P-C-B BMG with diameter of 2 mm combined with larger plastic strain and good soft magnetic properties. 14) To synthesize Febased BMGs with higher GFA and more excellent ductility, we tried to substitute part of Fe with Ni in Fe-Mo-P-C-B alloy system, basing on the consideration that nickel is soft and has ever been successfully substituted for Fe to enhance the GFA of Fe-based BMGs. 12) As a result, Fe-based BMGs with diameter up to 5 mm and plastic strain up to 4% are synthesized in Fe 74Àx Ni x Mo 6 P 10 C 7:5 B 2:5 alloy system.…”

Section: Introductionmentioning

confidence: 99%

Ductile Fe-Based BMGs with High Glass Forming Ability and High Strength

et al. 2008

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Fe-based bulk metallic glasses (BMGs) with high glass forming ability (GFA) and excellent mechanical properties were synthesized in FeNi-Mo-P-C-B alloy system by copper mold casting. Results show that the glass forming ability of Fe 74Àx Ni x Mo 6 P 10 C 7:5 B 2:5 alloys increases first and then decreases as Ni content, x, increases from 0 to 11.1 at%, with its climax being reached at x is between 3.7 and 5.0. Analyses indicate that either ÁT x and ÁH endo or T rg and can not illustrate the GFA of obtained alloys solely. With increasing Ni element in Fe 74Àx Ni x Mo 6 P 10 C 7:5 B 2:5 alloys, the yield strength and Vicker's mircrohardness decline, while the plasticity increases, which implies that enhancing plasticity by adjusting the composition of alloys is followed with the loss of some strength. Serrated flow characteristics on the compressive stress-strain curves is observed for Fe 74Àx Ni x Mo 6 P 10 C 7:5 B 2:5 as x ¼ 11:1 at%, which is considered to relate to its lowest glass transition temperature. These mechanical properties of BMGs are illustrated with bonding nature between the constituent elements.

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Ductile Fe-Based Bulk Metallic Glass with Good Soft-Magnetic Properties

Cited by 98 publications

References 21 publications

Role of Nb in glass formation of Fe–Cr–Mo–C–B–Nb BMGs

Role of Nb in glass formation of Fe–Cr–Mo–C–B–Nb BMGs

Glassy steel optimized for glass-forming ability and toughness

Ductile Fe-Based BMGs with High Glass Forming Ability and High Strength

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