Microstructures of Ni3 Al Rapidly Solidified by Hammer-Anvil Technique

AbstractThe Hammer-Anvil technique is employed for the rapid solidification of Ni3Al in the present work. The effect of off-stoichiometry on the change in the microstructure in the quenched alloy is examined for compositions within the L12 phase field at equilibrium. It is shown that non-equilibrium phases of various morphologies appear with fine grains of Ll2 phase, which have never been reported for the compound rapidly solidified by the roll techniques. With increasing aluminum concentration and with increase in cooling rate, the latter being judged by the difference in the thickness of the quenched foil, the fraction of the non-equilibrium phases appearing is found to increase giving more complex microstructure.

Microstructure and Properties of Rapidly Solidified Al-Zn-Mg-Cu Alloy

10.4028/www.scientific.net/msf.993.203 ◽

2020 ◽

Vol 993 ◽

pp. 203-207

Author(s):

Wei Min Ren ◽

Zi Yong Chen ◽

Zhi Lei Xiang ◽

Li Hua Chai

Keyword(s):

Aluminum Alloy ◽

Aluminum Alloys ◽

Cooling Rate ◽

Rapid Solidification ◽

Second Phase ◽

Alloy Strip ◽

Roller Speed ◽

Microstructure And Properties ◽

Cu Alloy ◽

Refining grain plays an important role in improving the mechanical properties of aluminum alloys. However, the conventional casting method with a slow cooling rate can be easy to cause coarseness of the microstructure and serious segregation. In this paper, the rapid solidification of Al-Zn-Mg-Cu alloy was prepared by the single-roller belt method. The alloy strip was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and hardness test to study the microstructure and properties of the rapidly solidified aluminum alloy. The results show that the roller speed was an important parameters affecting the formability of the alloy. When the roller speed was 15 m/s, the aluminum alloy produced a thin bandwidth of 5 mm and a thickness of 150 um. As the rotation speed of the roller increased, the cooling rate of the melt increased, and the microstructure of the rapidly solidified Al-Zn-Mg-Cu aluminum alloy strip improved in grains refinement. Compared with the conventionally cast Al-Zn-Mg-Cu aluminum alloys, the Al-Zn-Mg-Cu aluminum alloys prepared by rapid solidification showed much finer crystal grains, and enhanced solid solubility of alloying elements with less precipitation of second phase and high hardness.

Non- and Quasi-Equilibrium Multi-Phase Field Methods Coupled with CALPHAD Database for Rapid-Solidification Microstructural Evolution in Laser Powder Bed Additive Manufacturing Condition

Metals ◽

10.3390/met11040626 ◽

2021 ◽

Vol 11 (4) ◽

pp. 626

Author(s):

Sukeharu Nomoto ◽

Masahito Segawa ◽

Makoto Watanabe

Keyword(s):

Additive Manufacturing ◽

Cooling Rate ◽

Microstructural Evolution ◽

Phase Field ◽

Solidification Microstructure ◽

Quasi Equilibrium ◽

Cooling Rates ◽

Powder Bed ◽

Multi Phase ◽

A solidification microstructure is formed under high cooling rates and temperature gradients in powder-based additive manufacturing. In this study, a non-equilibrium multi-phase field method (MPFM), based on a finite interface dissipation model, coupled with the Calculation of Phase Diagram (CALPHAD) database, was developed for a multicomponent Ni alloy. A quasi-equilibrium MPFM was also developed for comparison. Two-dimensional equiaxed microstructural evolution for the Ni (Bal.)-Al-Co-Cr-Mo-Ta-Ti-W-C alloy was performed at various cooling rates. The temperature-γ fraction profiles obtained under 105 K/s using non- and quasi-equilibrium MPFMs were in good agreement with each other. Over 106 K/s, the differences between the non- and quasi-equilibrium methods grew as the cooling rate increased. The non-equilibrium solidification was strengthened over a cooling rate of 106 K/s. Columnar-solidification microstructural evolution was performed at cooling rates of 5 × 105 K/s to 1 × 107 K/s at various temperature gradient values under a constant interface velocity (0.1 m/s). The results show that, as the cooling rate increased, the cell space decreased in both methods, and the non-equilibrium MPFM was verified by comparing with the quasi-equilibrium MPFM. Our results show that the non-equilibrium MPFM showed the ability to simulate the solidification microstructure in powder bed fusion additive manufacturing.

Non- and Quasi-Equilibrium Multi-Phase Field Methods Coupled with CALPHAD Database for Rapid-Solidification Microstructural Evolution in Laser Powder Bet Additive Manufacturing Condition

10.20944/preprints202103.0295.v1 ◽

2021 ◽

Author(s):

Sukeharu Nomoto ◽

Masahito Segawa ◽

Makoto Watanabe

Keyword(s):

Additive Manufacturing ◽

Cooling Rate ◽

Microstructural Evolution ◽

Phase Field ◽

Solidification Microstructure ◽

Phase Field Method ◽

Quasi Equilibrium ◽

Cooling Rates ◽

Multi Phase ◽

Solidification microstructure is formed under high cooling rates and temperature gradients in powder-based additive manufacturing. In this study, a non-equilibrium multi-phase field method (MPFM), which was based on a finite interface dissipation model proposed by Steinbach et. al., coupled with a CALPHAD database was developed for a multicomponent Ni alloy. A qua-si-equilibrium MPFM was also developed for comparison. Two-dimensional equiaxed micro-structural evolution for the Ni (Bal.)–Al–Co–Cr–Mo–Ta–Ti–W–C alloy was performed at various cooling rates. The temperature–γ fraction profiles obtained under 10^5 K/s using non- and qua-si-equilibrium MPFMs were in good agreement with each other. Over 10^6 K/s, the differences between non- and quasi-equilibrium methods grew as the cooling rate increased. The non-equilibrium solidification was strengthened over a cooling rate of 10^6 K/s. Colum-nar-solidification microstructural evolution was performed under cooling rates from 5×10^5 K/s to 1×10^7 K/s at various temperature gradient values under the constant interface velocity (0.1 m/s). The results showed that as the cooling rate increased, the cell space decreased in both methods, and the non-equilibrium MPFM agreed well with experimental measurements. Our results show that the non-equilibrium MPFM can simulate solidification microstructure in powder bed fusion additive manufacturing.

A Phase-Field Model for Rapid Solidification with Non-Equilibrium Solute Diffusion

10.4028/www.scientific.net/msf.817.14 ◽

2015 ◽

Vol 817 ◽

pp. 14-20

Author(s):

Hai Feng Wang ◽

Cun Lai ◽

Xiao Zhang ◽

Kuang Wang ◽

Feng Liu

Keyword(s):

Rapid Solidification ◽

Phase Field ◽

Growth Velocity ◽

Field Model ◽

Phase Field Model ◽

Solute Diffusion ◽

Current Phase ◽

Diffusion Velocity ◽

Good Agreement ◽

Since the growth velocity can be comparable with or even larger than the solute diffusion velocity in the bulk phases, modeling of rapid solidification with non-equilibrium solute diffusion becomes quite an important topic. In this paper, an effective mobility approach was proposed to derive the current phase field model (PFM). In contrast with the previous PFMs that were derived by the so-called kinetic energy approach, diffusionless solidification happens not only in the bulk phases but also inside the interface when the growth velocity is equal to the solute diffusion velocity in liquid. A good agreement between the model predictions and experimental results is obtained for rapid solidification of Si-9at.%As alloy.

The Effect of Cooling Rate During Rapid Solidification on the Structure and Texture of NiTi

MRS Proceedings ◽

10.1557/proc-74-185 ◽

1986 ◽

Vol 74 ◽

Cited By ~ 1

Author(s):

A. J. Pedraza ◽

M. J. Godbole ◽

E. A. Kenik ◽

D. F. Pedraza ◽

D. H. Lowndes

Keyword(s):

Cooling Rate ◽

Rapid Solidification ◽

Heat Extraction ◽

X Ray Diffraction ◽

Rapid Solidification Technique ◽

Melted Layer ◽

Monoclinic Distortion ◽

Small Distortion ◽

B2 Phase ◽

AbstractA study has been conducted on the effects of increasing cooling rate during rapid solidification of NiTi upon the phases that are produced. The hammer and anvil rapid solidification technique and laser melting with a nanosecond excimer laser were used, which allow the cooling rate to be varied by three to four orders of magnitude. Although 1/3 {110} superlattice reflections are seen in the selected area diffraction (SAD) patterns of the splat quenched (SQ) specimens, x-ray diffraction analyses show the presence of only B2 phase and martensite. On the other hand, laser treatment (LT) of the specimens produces a layer that has a L10 structure with a slight monoclinic distortion. This phase can be envisaged as a small distortion of a B2 unit cell with a volume per atom ~3.3% lower than the equilibrium B2 phase. Also martensite is present in the layer. SQ alloys exhibit a marked {200} texture due to columnar growth opposite to the direction of heat extraction, while LT produces epitaxial regrowth of the melted layer. No substantial disordering is obtained in NiTi rapidly solidified alloys.

Microstructure Evolution in Rapidly Solidified Immiscible Alloys

10.4028/www.scientific.net/msf.508.37 ◽

2006 ◽

Vol 508 ◽

pp. 37-44 ◽

Cited By ~ 2

Author(s):

Michael Reuß ◽

Lorenz Ratke ◽

Jiu Zhou Zhao

Keyword(s):

Cooling Rate ◽

Nucleation Rate ◽

Particle Diameter ◽

Casting Process ◽

Average Particle ◽

Cooling Rates ◽

Gravity Casting ◽

The Difference ◽

Rapidly Solidified ◽

Mould Casting

We prepared Al-Bi alloys with our new aerogel counter gravity casting facility and Al-Pb alloys by simple mould casting with variable cooling rates. By counter gravity casting, it is possible to have directional solidification with flat isotherms and without forced melt flow during the casting process. Both methods allow studying the nucleation rate in liquid-liquid decomposition. The most important result is that a separation between monotectic and hypermonotectic particles is possible by using suitable cooling rates. The difference of the frequency maxima is a function, depending on cooling rate and starting composition. By casting experiments with variable cooling rates, we found that the average particle diameter is a function of the cooling rate, according to the theory of Ratke and Zhao, but the nucleation rate is higher than assumed in their theory.

Nucleation behaviour and microstructure of single Al-Si12 powder particles rapidly solidified in a fast scanning calorimeter

Journal of Materials Science ◽

10.1007/s10853-021-06096-6 ◽

2021 ◽

Author(s):

Bin Yang ◽

Qin Peng ◽

Benjamin Milkereit ◽

Armin Springer ◽

Dongmei Liu ◽

...

Keyword(s):

Cooling Rate ◽

Rapid Solidification ◽

Heterogeneous Nucleation ◽

Cooling Rates ◽

Solidification Behaviour ◽

Nucleation Undercooling ◽

In Situ Investigation ◽

Solidification Processes ◽

Powder Particles ◽

AbstractThe understanding of rapid solidification behaviour, e.g. the undercooling versus growth velocity relationship, is crucial for tailoring microstructures and properties in metal alloys. In most rapid solidification processes, such as additive manufacturing (AM), in situ investigation of rapid solidification behaviour is missing because of the lack of accurate measurement of the cooling rate and nucleation undercooling. In the present study, rapid solidification of single micro-sized Al-Si12 (mass%) particles of various diameters has been investigated via differential fast scanning calorimetry employing controllable cooling rates from 100 to 90,000 K s−1 relevant for AM. Based on nucleation undercooling and on microstructure analysis of rapidly solidified single powder particles under controlled cooling rates, two different heterogeneous nucleation mechanisms of the primary α-Al phase are proposed. Surface heterogeneous nucleation dominates for particles with diameter smaller than 23 μm. For particles with diameter larger than 23 μm, the nucleation of the primary α-Al phase changes from surface to bulk heterogeneous nucleation with increasing cooling rate. The results indicate that at large undercoolings (> 95 K) and high cooling rates (> 10,000 K s−1), rapid solidification of single particle can yield a microstructure similar to that formed in AM. The present work not only proposes new insight into rapid solidification processes, but also provides a theoretical foundation for further understanding of microstructures and properties in additively manufactured materials.

Microstructure of Rapidly Solidified Ti3Al Alloys

MRS Proceedings ◽

10.1557/proc-58-365 ◽

1985 ◽

Vol 58 ◽

Author(s):

A. G. Jackson ◽

K. R. Teal ◽

D. Eylon ◽

F. H. Froes ◽

S. J. Savage

Keyword(s):

Grain Size ◽

Rapid Solidification ◽

Phase Field ◽

Beta Phase ◽

Ingot Metallurgy ◽

Cooling History ◽

Alpha Beta ◽

Antiphase Domains ◽

20 Nm ◽

ABSTRACTThe microstructures of ordered Ti3Al-lZr (alpha2 +Zr) and Ti-Al-Nb alloys produced by ingot metallurgy (IM) and by rapid solidification (RS) are compared. The RS Ti3Al-iZr (alpha2 structure) alloy displayed small antiphase domains (APD) of 10–20 nm in the as-produced condition, but large grain size. The latter observation is rationalized in terms of the cooling history used to produce the material. The RS Ti-Al-Nb alloy exhibited an equiaxed microstructure. The IM Ti-Al-Nb material displays a complete change in microstructure between 1010°C and 1035°C, indicating a narrow alpha+beta phase field.

Metastable ordered austenite in rapidly solidified Fe-Al-C alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015455x ◽

1989 ◽

Vol 47 ◽

pp. 516-517

Author(s):

J. A. Sarreal

Keyword(s):

Rapid Solidification ◽

Melt Spinning ◽

X Ray Diffraction ◽

Austenitic Phase ◽

X Ray ◽

Transmission Electron ◽

Melt Spun ◽

Melt Spun Ribbons ◽

Equilibrium Phases ◽

Conventionally cast Fe-Al-C alloys are extremely brittle containing combinations of ferrite, carbide and other phases. Rapid solidification has the potential of altering the microstructure to subsequently change the resulting mechanical properties. An apparent conflict exist concerning the effect of rapid solidification on the resulting microstructure of these alloys. Inoue and co-workers, using transmission electron microscopy (TEM) and electron diffraction analyses, reported the presence of several non-equilibrium phases including austenite (fcc - γ) and ordered austenite (Ll2-γ') structures on alloys containing 1.7 to 2.1 C and 6 to 12 Al in weight % (w/o) on melt spun ribbons 30 μm in thickness. Han and Choo, using x-ray diffraction analysis on 30-48 μm thick melt spun ribbons concluded that this ordered fee phase is rather an austenitic phase in which phase decomposition accompanied by sideband phenomenon had occured.Single roller melt spinning technique was used to make ribbons 35-70 μm thick and 0.5-5 mm wide. X-ray diffration analysis showed single phase austenite for samples 2-6 w/o AI and 2 w/o C. Samples with 8-10 w/o AI and 2 w/o C also showed several superlattice lines in addition to the fundamental fcc peaks.

Cooling Rate and Microstructural Investigation of Rapidly Solidified Spherical Mono-Sized Copper Particles

10.4028/www.scientific.net/msf.976.42 ◽

2020 ◽

Vol 976 ◽

pp. 42-49

Author(s):

Ying Yan Hu ◽

Jun Feng Wang ◽

Can Li ◽

Yi Ying Gao ◽

Jian Qiang Li

Keyword(s):

Grain Boundary ◽

Cooling Rate ◽

Rapid Solidification ◽

Particle Diameter ◽

Spherical Shape ◽

Microstructural Investigation ◽

Argon Gas ◽

Copper Particles ◽

Rapidly Solidified ◽

The Relationship

Spherical copper particles with diameter ranging from 120.6 to 437.0 μm were prepared by the pulsated orifice ejection method (termed “POEM”). These spherical copper particles exhibit a good spherical shape and a narrow size distribution, suggesting that the liquid copper can completely break the balance between the surface tension and the liquid static pressure in the crucible micropores and accurately control the volume of the droplets. Furthermore, the relationship between cooling rate and microstructures of spherical copper particles was carried out with a specific focus on different cooling atmosphere and particle diameter during the rapid solidification. The cooling rate of spherical copper particles is evaluated by a Newton’s cooling model. It is revealed that the cooling rate was depended on cooling medium and particle diameter. The cooling rate decreases and the grain size increases with the increase of particle diameter during the rapid solidification, while the grain boundary of same particle diameter with larger cooling rate in argon gas is smaller, while the grain boundary of particles with smaller cooling rate in helium gas is larger. When the particle diameter is larger than 100 μm, the cooling rate of the cooper droplet in argon gas achieves 1.0×104 K/s. Meanwhile, the cooling rate decreases rapidly when the particle diameter increased between 70.6 and 149.6 μm. It is an effective route for fabrication of high-quality spherical copper particles.