A bridge from monotectic alloys to liquid-phase-separated bulk metallic glasses: Design, microstructure and phase evolution

He, Jiasong; Mattern, N.; Tan, Jieqing; Zhao, Jingjing; Kaban, I.; Wang, Zhi; Ratke, Lorenz; Kim, D.H.; Kim, W.T.; Eckert, J.

doi:10.1016/j.actamat.2012.12.031

Cited by 54 publications

(19 citation statements)

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“…A pertinent question is how to understand these systemspecific behaviours in a general physical scenario. To appreciate this question, we consider the concept of enthalpy of mixing for MGs as it provides an effective way to the understanding of many chemical-related issues in MGs, such as glass-forming ability 33,34 , mechanical properties 37 , phase separation [38][39][40] , as well as crystallization and devitrification of MGs 41 . Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Three typical MG systems with 10 different compositions were selected for experiments; these are La 70 (Cu x Ni 1-x ) 15 Al 15 with x ¼ 0, 0.5, 0.67 and 1; Pd 40 (Cu x Ni 1-x ) 40 P 20 with x ¼ 0 and 0.75; and (Cu 0.5 Zr 0.5 ) 100-x Al x with x ¼ 0, 4, 8 and 10, respectively; because of their markedly different relaxation behaviours that are representative for most known MGs. The La-based and CuZr-based MGs are prepared by Cu-mold casting method: the raw materials were melted in a Tigettered argon atmosphere and subsequently cast into a water-cooled Cu-mold.…”

Section: Methodsmentioning

confidence: 99%

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Chemical influence on β-relaxations and the formation of molecule-like metallic glasses

et al. 2013

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Secondary (also known as Johari-Goldstein or b-) relaxations are an intrinsic feature of supercooled liquids and glasses. They are important in many respects but the underlying mechanisms are not well understood. A long-standing puzzle is why some glasses show b-relaxations as pronounced peaks, whereas others as unobvious excess wings. Here we demonstrate that these different behaviours are related to the fluctuations of chemical interactions by using prototypical systems of metallic glasses. A general rule is summarized: pronounced b-relaxations are associated with systems where all the atomic pairs have large similar negative values of enthalpy of mixing, whereas positive or significant fluctuations in enthalpy of mixing suppress b-relaxations. The emerging physical picture is that strong and comparable interactions among all the constituting atoms maintain string-like atomic configurations for the excitations of b-events and can be considered as the formation of molecule-like metallic glasses.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Chemical influence on β-relaxations and the formation of molecule-like metallic glasses

et al. 2013

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“…It results in the separation of one homogeneous liquid phase into two or more immiscible liquid phases. Up to now, there have been extensive investigations on the liquid phase separation of immiscible alloys [1][2][3][4]. The surface segregation of solutes and the Marangoni migration as well as the Stokes motion of secondary droplets have been shown to be the main factors in influencing the final microstructures [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Solute redistribution during phase separation of ternary Fe–Cu–Si alloy

et al. 2015

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Ternary Fe 48 Cu 48 Si 4 immiscible alloy was rapidly solidified under the containerless microgravity condition inside a drop tube. Liquid phase separation took place in the alloy melt and led to the formation of various segregated structures. The core-shell structure consisting of Fe-rich and Cu-rich zones and the homogenously dispersed structure were the major structural morphologies. Phase field simulation results revealed that the two-layer core-shell was the final structure of liquid phase separation. The solute redistribution of liquid Fe 48 Cu 48 Si 4 alloy experienced the macroscopic solute distribution induced by liquid phase separation, the secondary phase separation within the separated liquid phases and the solute trapping during rapid solidification. Energy dispersive spectroscopy analysis showed that the solute Si was enriched in the Ferich zone whereas depleted in the Cu-rich zone. In addition, both aFe and (Cu) phases in the Fe-rich zone exhibited a conspicuous solute trapping effect. As compared with (Cu) phase, aFe phase had a stronger affinity with solute Si.

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“…the liquid drops become amorphous or crystalline. In recent years such novel amorphous/amorphous [10][11][12][13] or amorphous / crystalline [14-16] composites have been synthesized.…”

Section: Introductionmentioning

confidence: 99%

“…the liquid drops become amorphous or crystalline. In recent years such novel amorphous/amorphous [10][11][12][13] or amorphous / crystalline [14-16] composites have been synthesized.Our subject is the study of the liquid immiscibility in the Ag-Cu-Zr system, in which the homogenous liquid separates into an Ag-rich liquid (L 1 ) and into a Cu-Zr-rich liquid (L 2 ) during cooling through the miscibility gap [17][18]. In the present work nickel (Ni) and yttrium (Y) are separately added to the Ag-Cu-Zr system and their influence is studied on liquid immiscibility.…”

mentioning

confidence: 99%

Effect of Y and Ni addition on liquid immiscibility in Cu–Zr–Ag ternary alloys

Janovszky

Tomolya

Svéda

et al. 2014

Journal of Alloys and Compounds

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Liquid immiscibility was studied in Cu-Zr-Ag-Y and Cu-Zr-Ag-Ni liquid alloy systems. In case of Y addition the liquid decomposes into an Ag-Y rich liquid (L 1 ) and into a Cu-Zr rich liquid (L 2 ). In case of Ni addition the separated liquid phases are Ag-rich and Cu-Zr-Ni rich liquids. Different microstructures were found as function of the volume fraction of the L 1 liquid phase. The Y addition increased the field of miscibility gap of the ternary Cu-Zr-Ag system to a greater extent compared to Ni addition. Also, the rate of coalescence of droplets in the Cu-Zr-Ag-Y system was considerably larger compared to the Cu-Zr-Ag-Ni system. These two observations are interconnected: increased miscibility means more positive excess Gibbs energy, which leads to higher liquid/liquid interfacial energy, being the driving force of coalescence. Alloys with different compositions taken from the tip of the wedge have been studied by DSC. The amorphous fraction progressively reduces when increasing the Ag-content. A small amount of amorphous phase was detected by DSC in the alloy with Ag contents of not greater than 50 at%.Keywords: Ag-Cu-Zr alloy, Liquid-liquid separation, Miscibility gap, Monotectic, Rapid solidification IntroductionCopper-zirconium (Cu-Zr) bulk metallic glasses (BMGs) have been developed due to their lower cost compared to Zr-based BMGs [1-6]. As the BMGs are quite brittle, their further development was necessary to improve their ductility, which can be achieved in three ways: either by extrinsically adding a second crystalline phase to the amorphous matrix [7] or by intrinsic phase separation [8] or by partial nanocrystallization of the amorphous matrix [9]. It is worth noting that the second phase`s shape and morphology are also very important parameters affecting mechanical properties. The second phase with sharp edges is a stress concentration site, so it reduces toughness. In contrast a spherical second phase improves the mechanical properties. The liquid phase separation meets these requirements: i. the separated phase forms spherical, generally liquid drops; ii. the liquid drops become amorphous or crystalline. In recent years such novel amorphous/amorphous [10][11][12][13] or amorphous / crystalline [14-16] composites have been synthesized.Our subject is the study of the liquid immiscibility in the Ag-Cu-Zr system, in which the homogenous liquid separates into an Ag-rich liquid (L 1 ) and into a Cu-Zr-rich liquid (L 2 ) during cooling through the miscibility gap [17][18]. In the present work nickel (Ni) and yttrium (Y) are separately added to the Ag-Cu-Zr system and their influence is studied on liquid immiscibility. These two alloying elements have been chosen to check the effect of the heat of mixing between silver (Ag) and the given element: the heat of mixing in the Ag-Y system is highly negative [19]) while that in the Ag-Ni system is positive [20].

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A bridge from monotectic alloys to liquid-phase-separated bulk metallic glasses: Design, microstructure and phase evolution

Cited by 54 publications

References 50 publications

Chemical influence on β-relaxations and the formation of molecule-like metallic glasses

Chemical influence on β-relaxations and the formation of molecule-like metallic glasses

Solute redistribution during phase separation of ternary Fe–Cu–Si alloy

Effect of Y and Ni addition on liquid immiscibility in Cu–Zr–Ag ternary alloys

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