Synthesis of iron-based bulk metallic glasses as nonferromagnetic amorphous steel alloys

Ponnambalam, V.; Poon, S. J.; Shiflet, G. J.; Keppens, Veerle; Taylor, Rosemary; Petculescu, Gabriela

doi:10.1063/1.1599636

Cited by 184 publications

(93 citation statements)

References 11 publications

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“…As discussed by Ponnambalam et al, 25 the alloy development strategy that led to the bulk-glasses in Refs. 1 and 2 relied on attaining structurally rigid liquid configurations through heavy alloying.…”

Section: T G ͑°C͒mentioning

confidence: 99%

“…1 and 2 relied on attaining structurally rigid liquid configurations through heavy alloying. Structural reinforcement of the equilibrium liquid, they argue, is associated with the formation of a "backbone" liquid structure which gives rise to higher T g and higher isoconfigurational G. Ponnambalam et al 25 therefore imply that such alloy development strategy relies on dramatically increasing W. In the present approach, bulkglass-forming compositions were derived directly from Fe 80 P 12.5 C 7.5 , a tough yet marginal glass former exhibiting a rather low T g and G. As shown in Table I, the present compositions are designed to improve glass-forming ability with respect to the parent Fe 80 P 12.5 C 7.5 without raising T g and G.…”

Section: T G ͑°C͒mentioning

confidence: 99%

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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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Section: T G ͑°C͒mentioning

confidence: 99%

Section: T G ͑°C͒mentioning

confidence: 99%

Glassy steel optimized for glass-forming ability and toughness

Demetriou¹,

Kaltenboeck²,

Suh³

et al. 2009

Applied Physics Letters

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“…Nevertheless, these ordinary-late-transition-metal-based BMGs generally have quite limited glass-forming ability (GFA). Their favored single-amorphous-phase structures get compromised and undesired first-order phase transitions start to intervene once their casting thickness (or diameter) exceeds a critical value 5 mm (or lower) [3][4][5][6][7][8][9][10][11]. In contrast, this critical value of thickness for many early-transition-metal-based BMGs to sustain their fully glassy structures can reach as high as several centimeters [12 -15].…”

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Unusual Glass-Forming Ability of Bulk Amorphous Alloys Based on Ordinary Metal Copper

2004

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We report the unusual glass-forming ability (GFA) of a family of Cu-based alloys, Cu 46 Zr 47ÿx Al 7 Y x (0 < x 10, in at. %), and investigate the origin of this unique property. By an injection mold casting method, these alloys can be readily solidified into amorphous structures with the smallest dimension ranging from 4 mm up to 1 cm without detectable crystallinity. Such superior GFA is found primarily due to the alloying effect of Y, which lowers the alloy liquidus temperature and brings the composition closer to a quaternary eutectic. Other beneficial factors including appropriate atomic-size mismatch and large negative heat of mixing among constituent elements are also discussed. DOI: 10.1103/PhysRevLett.92.245504 PACS numbers: 61.43.Dq, 61.10.Nz, 65.60.+a, 81.05.Kf Bulk amorphous alloys (also known as BMGs: bulk metallic glasses) have been drawing increasing attention in recent years due to their scientific and engineering significance [1,2]. A great deal of effort in this area has been devoted to developing BMGs in different alloy systems. BMGs based on certain late transition metals (e.g., Fe, Co, Ni, Cu) have many potential advantages over those based on early transition metals. These include even higher strength and elastic moduli, and lower materials cost, to name a few, which are highly preferable for a broad application of BMGs as engineering materials. Nevertheless, these ordinary-late-transition-metal-based BMGs generally have quite limited glass-forming ability (GFA). Their favored single-amorphous-phase structures get compromised and undesired first-order phase transitions start to intervene once their casting thickness (or diameter) exceeds a critical value 5 mm (or lower) [3][4][5][6][7][8][9][10][11]. In contrast, this critical value of thickness for many early-transition-metal-based BMGs to sustain their fully glassy structures can reach as high as several centimeters [12 -15].Very recently, BMGs have surprisingly been found in the binary Cu-Zr system by several groups [10,11,16,17], among which Cu 46 Zr 54 has a critical casting thickness up to 2 mm, highest within its local compositional vicinity [16]. The discovery of these binary BMGs strongly suggests that even higher GFA may be achievable in Cubased alloys by appropriately introducing additional alloying elements. As a matter of fact, Inoue et al. reported earlier [18] that the critical casting thickness of certain ternary Cu-based alloys in a Cu-Zr-Al system is 3 mm. Following the ''confusion principle'' proposed by Greer [19], we further examined the effects of other alloying elements on the GFA of a preselected ternary alloy Cu 46 Zr 47 Al 7 (''matrix alloy'' in the following context). In this Letter, we report a series of quaternary Cubased alloys, Cu 46 Zr 47ÿx Al 7 Y x (0 < x 10, in at. %), which possess unusually high GFA. The amorphous structure of a representative alloy Cu 46 Zr 42 Al 7 Y 5 can be readily obtained even when the casting diameter exceeds 1 cm.The possible mechanisms involved in the achievement of this unusu...

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“…In the last two decades, several alloys based on Pd, 1-3 La, 4 Zr, 5,6 Fe, [7][8][9] and Pt 10 were found to form bulk amorphous phases. Fully amorphous samples are obtained when the alloys are cast into copper molds of diameter up to centimeters which indicates critical cooling rates for glass formation of 100 K / s or less.…”

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Gold based bulk metallic glass

Schroers

Lohwongwatana

Johnson

et al. 2005

Applied Physics Letters

229

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Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5 mm in the best glassformer. Au 49 Ag 5.5 Pd 2.3 Cu 26.9 Si 16.3 has a liquidus temperature of 644 K, a glass transition temperature of 401 K, and a supercooled liquid region of 58 K. The Vickers hardness of the alloys in this system is ϳ350 Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry. Gold became known to mankind thousands years ago, and has been of inestimable value to civilization ever since. It is the noblest of the noble metals, and has a good combination of high thermal conductivity, high electrical conductivity, and high corrosion resistance. These properties have resulted in extensive use of gold and its alloys in electronic, aerospace, astronomy, medical, and industrial applications. For instance, gold can be found in many of today's sophisticated electronic devices. However, gold has always been most valued as a jewelry material. Gold alloys are easy to fashion, are nonallergenic, have a bright pleasing color, and remain tarnish free indefinitely. Pure gold and higher karat gold alloys, however, are rather soft and therefore vulnerable to wear and scratching. This results in diminished aesthetic appearance, and is a drawback of conventional crystalline gold alloys.In the last two decades, several alloys based on Pd, 1-3 La, 4 Zr, 5,6 Fe, 7-9 and Pt 10 were found to form bulk amorphous phases. Fully amorphous samples are obtained when the alloys are cast into copper molds of diameter up to centimeters which indicates critical cooling rates for glass formation of 100 K / s or less. These bulk metallic glasses ͑BMGs͒ exhibit properties such as high strength, large elastic strain limit, high hardness, and, in some cases, substantial ductility. 11 The compositions of these BMGs are typically close to a deep eutectic composition. Consequently, their melting temperatures are much lower than estimated from interpolation of the alloy constituents' melting temperatures. The resulting low liquidus temperature is an attractive property for casting alloys. The extraordinary stability of BMG forming alloys against crystallization also results in a large supercooled liquid region, ⌬T, ͑⌬T = T x -T g , T x : crystallization temperature, T g : glass transition temperature͒, the temperature region in which the amorphous phase first relaxes into a highly viscous liquid before eventually crystallizing.In this temperature region, BMG's are amenable to superplastic processing using netshape processing methods similar to those employed for thermoplastics. 12 The binary gold silicon eutectic composition was the first alloy found to exhibit metallic glass formation by Duwez and co-workers in ...

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Synthesis of iron-based bulk metallic glasses as nonferromagnetic amorphous steel alloys

Cited by 184 publications

References 11 publications

Glassy steel optimized for glass-forming ability and toughness

Glassy steel optimized for glass-forming ability and toughness

Unusual Glass-Forming Ability of Bulk Amorphous Alloys Based on Ordinary Metal Copper

Gold based bulk metallic glass

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