Selection of Dedicated As-Cast Microstructures in Zn-Al-Cu Alloys for Bearing Applications Supported by Phase-Field Simulations

Solidification and phase formation of Zn-rich Zn-Al-Cu alloys with different Al and Cu contents were investigated. The investigations comprise alloy compositions with either hcp η, fcc α or hcp ε as the primary phase, as well as a composition close to the ternary eutectic point. Test samples were produced in a mold casting process and their microstructures were investigated by scanning electron microscopy. Experimental microstructures are compared with the results from spatially resolved microstructure simulations using a phase-field model. In particular, the dependency between the aluminum and copper contents and the phase fractions of the η, α and ε phases were analyzed. In addition, hardness tests for the samples prove a direct correlation between the α- and ε-phase fractions with the macroscopic hardness of the alloys. A simple model, based on the phase fractions and the properties of the single phases, is suggested for the computation of hardness from the simulation results in order to select appropriate alloy compositions for bearing applications.

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Study of solidification pathway of a MoSiBTiC alloy by optical thermal analysis and in-situ observation with electromagnetic levitation

Scientific Reports ◽

10.1038/s41598-019-50945-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 3

Author(s):

Hiroyuki Fukuyama ◽

Ryogo Sawada ◽

Haruki Nakashima ◽

Makoto Ohtsuka ◽

Kyosuke Yoshimi

Keyword(s):

Eutectic Reaction ◽

Ternary Eutectic ◽

Eutectic Point ◽

Electromagnetic Levitation ◽

Primary Phase ◽

In Situ Observation ◽

Molybdenum Boride ◽

Ultrahigh Temperature ◽

Solidification Pathway

Abstract MoSiBTiC alloys are promising candidates for next-generation ultrahigh-temperature materials. However, the phase diagram of these alloys has been unknown. We have developed an ultrahigh-temperature thermal analyser based on blackbody radiation that can be used to analyse the melting and solidification of the alloy 67.5Mo–5Si–10B–8.75Ti–8.75 C (mol%). Furthermore, electromagnetic levitation (EML) was used for in-situ observation of solidification and microstructural study of the alloy. On the basis of the results, the following solidification pathway is proposed: Mo solid solution (Moss) begins to crystallize out as a primary phase at 1955 °C (2228 K) from a liquid state, which is followed by a (Moss+TiC) eutectic reaction starting at 1900 °C (2173 K). Molybdenum boride (Mo2B) phase precipitates from the liquid after the eutectic reaction; however, the Mo2B phase may react with the remaining liquid to form Moss and Mo5SiB2 (T2) as solidification proceeds. In addition, T2 also precipitates as a single phase from the liquid. The remaining liquid reaches the (Moss + T2 + TiC) ternary eutectic point at 1880 °C (2153 K), and the (Moss + T2 + Mo2C) eutectic reaction finally occurs at 1720 °C (1993 K). This completes the solidification of the MoSiBTiC alloy.

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An integrated crystal plasticity–phase field model for spatially resolved twin nucleation, propagation, and growth in hexagonal materials

International Journal of Plasticity ◽

10.1016/j.ijplas.2018.03.009 ◽

2018 ◽

Vol 106 ◽

pp. 203-227 ◽

Cited By ~ 57

Author(s):

C. Liu ◽

P. Shanthraj ◽

M. Diehl ◽

F. Roters ◽

S. Dong ◽

...

Keyword(s):

Crystal Plasticity ◽

Phase Field ◽

Field Model ◽

Phase Field Model ◽

Spatially Resolved ◽

Twin Nucleation ◽

Hexagonal Materials

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CALPHAD-informed phase-field model for two-sublattice phases based on chemical potentials: η-phase precipitation in Al-Zn-Mg-Cu alloys

Acta Materialia ◽

10.1016/j.actamat.2021.117602 ◽

2021 ◽

pp. 117602

Author(s):

Chuanlai Liu ◽

Alec Davis ◽

Jonathan Fellowes ◽

Philip B. Prangnell ◽

Dierk Raabe ◽

...

Keyword(s):

Phase Field ◽

Field Model ◽

Phase Field Model ◽

Phase Precipitation ◽

Chemical Potentials ◽

Cu Alloys

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Phase Relations of the Bi-2201–CuO Pseudobinary Join as a Function of Oxygen Pressure

MRS Proceedings ◽

10.1557/proc-659-ii2.4 ◽

2000 ◽

Vol 659 ◽

Author(s):

James K. Meen ◽

Karoline Müller ◽

Celia Salmeron ◽

Don Elthon

Keyword(s):

Phase Field ◽

Ternary Phase ◽

Invariant Point ◽

Freezing Point ◽

Ternary Eutectic ◽

Primary Phase ◽

Phase Relations ◽

Primary Phase Field ◽

Freezing Point Depression ◽

Narrow Temperature Range

ABSTRACTPhase relations on the join Bi-2201–CuO have been determined as a function of P(O2). Most of the major changes that occur between P(O2) of 1 and 0.01 atm occur in the most oxidizing part of the range. Stoichiometric Bi-2201 occurs only at the most oxidizing conditions and in a narrow temperature range near the solidus. In the Bi-2201–CuO system, the ternary phase that forms has higher Bi:Sr and Cu:Sr than Bi-2201. That phase, Sr14Cu24Oy, and CuO occur in the subsolidus and the invariant point at which they coexist with liquid is a ternary eutectic. The liquid is more Sr-rich than the Bi-2201–CuO join. Decrease in P(O2) produces a change in the Bi- 2201 solid solution so that stoichiometric Bi-2201 does not occur. At P(O2) ≤0.5 atm, all Bi- 2201 solid solutions have Bi:Cu<2 but Bi:Sr near unity and Sr14Cu24Oy does not form. Small amounts of a phase believed to be Bi9Sr11Cu5Ox form under these conditions and the primary phase field of that phase crosses the pseudobinary join and minimum melting is at a ternary tributary reaction point. The liquid there is more Bi-rich than the join. Further decrease in P(O2) causes a continued freezing point depression and enlargement of the CuO primary phase field so that the compositions of multiply-saturated liquids move away from the CuO apex.

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Microstructure Evolution of a Directionally Solidified Ternary Eutectic Mo-Si-B Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.1226 ◽

2016 ◽

Vol 879 ◽

pp. 1226-1232 ◽

Cited By ~ 1

Author(s):

Manja Krüger ◽

Georg Hasemann ◽

Omid Kazemi ◽

Thorsten Halle

Keyword(s):

High Temperature ◽

Field Model ◽

Ternary Eutectic ◽

Phase Field Model ◽

Eutectic Point ◽

Zone Melting ◽

Eutectic Phase ◽

Nominal Composition ◽

Directionally Solidified ◽

Isotropic Model

The aim of the present study is to identify the ternary eutectic Mo-Si-B composition to produce directionally solidified materials, which are expected to have excellent high-temperature properties due to the well-defined microstructure. Different alloy compositions in the respective primary solidification areas of the phases were chosen to investigate the microstructural evolution. The results were compared to thermodynamic calculations of the liquidus projection and isopleth phase diagrams using the software FactSageTM. By carrying out these experiments the eutectic point was found to have a nominal composition of Mo-17.5Si-8B (at.%). In the next step, the eutectic alloy was directionally solidified by a zone melting (ZM) process. The evolution of a typical eutectic microstructure due to the growth of lamella-like structures is shown by microstructural investigations. Furthermore, we present a eutectic phase field model for the eutectic Mo-Si-B alloy. The equilibrium interface geometries and interface mobility were calculated using an isotropic model. The results are shown to be in an adequate conformity with the experimental observations.

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Formation of Primary Intermetallic Compounds in Sn-Ag-Cu Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1397 ◽

2010 ◽

Vol 654-656 ◽

pp. 1397-1399 ◽

Cited By ~ 3

Author(s):

Yoshiko Takamatsu ◽

Hisao Esaka ◽

Kei Shinozuka

Keyword(s):

Liquid Phase ◽

Intermetallic Compounds ◽

Ternary Eutectic ◽

Equilibrium Phase ◽

Solidification Process ◽

Equilibrium Phase Diagram ◽

Primary Phase ◽

Cu Alloys ◽

Binary Eutectic ◽

Free Solder

Sn-Ag-Cu alloys are considered one of the most favorable lead-free solder systems. In slowly-cooled eutectic Sn-Ag-Cu alloys, sometimes large primary Ag3Sn or Cu6Sn5 intermetallic compounds (IMCs) form. These IMCs may affect the mechanical properties of solders. However, explanations for the formation of these IMCs are still not clear. This study deals with interrupted tests in order to clarify the nucleation of IMCs in the liquid phase. In this study, Sn-4.41Ag-0.63Cu and Sn-3.30Ag-1.47Cu alloys were prepared. According to the thermodynamic calculation, Pandat, the equilibrium solidification paths are described as follows: Sn-4.41Ag-0.63Cu :L → primary Ag3Sn → binary eutectic (Ag3Sn +Sn) → ternary eutectic; Sn-3.30Ag-1.47Cu :L → primary Cu6Sn5 → binary eutectic (Cu6Sn5 + Sn)→ ternary eutectic. The actual solidification process was different from the estimation from the equilibrium phase diagram. In the case of Sn-4.41Ag-0.63Cu, only Ag3Sn grew as a primary phase in the liquid, while in the case of Sn-3.30Ag-1.47Cu, not only primary Cu6Sn5 but also pseudo-primary Ag3Sn grew in the liquid. Ag3Sn may nucleate easily in the liquid phase, but Cu6Sn5 would not nucleate in the liquid.

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