Thermal Parameters, Microstructure and Porosity During Transient Solidification of Ternary Al–Cu–Si Alloys

Solidification of ternary Al-Cu-Si alloys begins with the development of a complex dendritic network typified by primary (λ1) and secondary (λ2) dendrite arm spacings which depend on the chemical composition of the alloy and on the casting thermal parameters such as the growth rate and the cooling rate. These thermal parameters control the scale of dendritic arms, the size and distribution of porosity and intermetallic particles in the casting. In this paper, λ1and λ2were correlated with experimental thermal parameters i.e., the tip growth rate and the tip cooling rate. The porosity profile along the casting length has also been experimentally determined. The volumetric fraction of pores increase with the increase in alloying Si and with the increase in Fe concentration at the regions close to the casting cooled surface.

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Influence of thermal parameters on the dendritic arm spacing and the microhardness of Al-5.5wt.%Sn alloy directionally solidified

Rem Revista Escola de Minas ◽

10.1590/s0370-44672014000200007 ◽

2014 ◽

Vol 67 (2) ◽

pp. 173-179 ◽

Cited By ~ 4

Author(s):

Angela de Jesus Vasconcelos ◽

Cibele Vieira Arão da Silva ◽

Antonio Luciano Seabra Moreira ◽

Maria Adrina Paixão de Sousa da Silva ◽

Otávio Fernandes Lima da Rocha

Keyword(s):

Growth Rate ◽

Aluminum Alloys ◽

Cooling Rate ◽

Thermal Parameters ◽

The Other ◽

Directionally Solidified ◽

Dendritic Microstructure ◽

Dendritic Network ◽

Dendritic Arm Spacing ◽

The Relationship

Al-Sn alloys are widely used in tribological applications. In this study, thermal, microstructural and microhardness (HV) analysis were carried out with an Al-5.5wt.%Sn alloy ingot produced by horizontal directional transient solidification. The main parameters analyzed include the growth rate (V L) and cooling rate (T R).These thermal parameters play a key role in the microstructural formation. The dendritic microstructure has been characterized by primary dendritic arm spacing (λ1) which was experimentally determined and correlated with V L, and T R. The behavior presented by the Al-5.5wt.%Sn alloy during solidification was similar to that of other aluminum alloys, i.e., the dendritic network became coarser with decreasing cooling rates, indicating that the immiscibility between aluminum and tin does not have a significant effect on the relationship between primary dendritic arm spacing and the cooling rate. The dependence of the microhardness on V L, T R and λ1 was also analyzed. It was found that for increasing values of T R, the values of HV decrease. On the other hand, the values of HV increase with increasing values of λ1.

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Microstructural Evolution during the Directional Transient Solidification of a Hypomonotectic Al-0.9wt%Pb Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.730-732.829 ◽

2012 ◽

Vol 730-732 ◽

pp. 829-834

Author(s):

Adrina P. Silva ◽

Pedro R. Goulart ◽

José Eduardo Spinelli ◽

Amauri Garcia

Keyword(s):

Growth Rate ◽

Heat Flow ◽

Thermal Parameters ◽

Cooling Curves ◽

Flow Conditions ◽

Directionally Solidified ◽

Microstructural Transition ◽

Transient Heat Flow ◽

Growth Laws ◽

Casting Length

In the present study a hypomonotectic Al-0.9wt%Pb alloy was directionally solidified under transient heat flow conditions and the microstructure evolution was analyzed. The solidification thermal parameters such as the growth rate, the cooling rate and the temperature gradient were experimentally determined by cooling curves recorded by thermocouples positioned along the casting length. The monotectic structure was characterized by metallography and a microstructural transition was observed. From the casting cooled surface up to a certain position in the casting the microstructure was characterized by well-distributed Pb-rich droplets in the aluminum-rich matrix, followed by a mixture of fibers and strings of pearls from this point to the top of the casting. The interphase spacing (λ) and the diameter of Pb-rich particles were also measured along the casting length and experimental growth laws relating these microstructural features to the experimental thermal parameters are proposed.

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Unsteady-State Directional Solidification of a Hypoperitectic Pb-9.5wt%Bi Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.730-732.889 ◽

2012 ◽

Vol 730-732 ◽

pp. 889-894

Author(s):

Manuel Antonio Pires Castanho ◽

Pedro R. Goulart ◽

Noé Cheung ◽

Amauri Garcia

Keyword(s):

Growth Rate ◽

Dendritic Morphology ◽

Thermal Parameters ◽

Cooling Curves ◽

Unsteady State ◽

Flow Conditions ◽

Directionally Solidified ◽

Growth Laws ◽

Casting Length ◽

Continuous Temperature

Although considerable attention has been paid to studies on the unidirectional solidification of peritectic alloys, most of these investigations are carried out under steady-state solidification, where both the growth rate and the thermal gradient can be independently controlled and held constant in time. In this work, a hypoperitectic Pb-9.5wt%Bi alloy was directionally solidified under unsteady-state heat flow conditions and the microstructure evolution was analyzed. Continuous temperature measurements in the casting were monitored during solidification, using a data acquisition system and a bank of six type J thermocouples positioned along the casting length. Thermal parameters such as the growth rate (v) and the cooling rate () were experimentally determined by the experimental cooling curves. The solidification microstructure was characterized by a dendritic morphology along the entire casting length. The primary (l1) and secondary (l2) dendrite arm spacings were measured and experimental growth laws relating them to the solidification thermal parameters v and are proposed.

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The columnar to equiaxed transition in the directional solidification of aluminum based multicomponent alloys

Rem Revista Escola de Minas ◽

10.1590/0370-44672015680237 ◽

2015 ◽

Vol 68 (1) ◽

pp. 85-90 ◽

Cited By ~ 4

Author(s):

Otávio Lima Rocha ◽

Laércio Gouvea Gomes ◽

Daniel Joaquim Conceição Moutinho ◽

Ivaldo Leão Ferreira ◽

Amauri Garcia

Keyword(s):

Cooling Rate ◽

Tip Growth ◽

Solute Concentration ◽

Unidirectional Solidification ◽

Unsteady State ◽

Flow Conditions ◽

Multicomponent Alloys ◽

Vertical Solidification ◽

Columnar To Equiaxed Transition ◽

Si Content

In this work the columnar to equiaxed transition (CET) was experimentally investigated in the unidirectional solidification of three aluminum based multicomponent alloys (Al-nSi-3Cu), with "n" equal to 5.5, 7.5 and 9 wt.%. The main parameters analyzed include the tip temperature gradient (GL), tip growth rate (VL), tip cooling rate (TR) and Si content. A water-cooled solidification experimental setup was developed, and specimens were solidified under unsteady state heat flow conditions. It is shown that for the alloys examined, the solute concentration influences the position of the CET, which occurs for an average cooling rate of about 1.17 0C/s. A comparative analysis between the results of this work and those from literature proposed to analyze the CET during upward vertical solidification of Al-Si alloys is reported and the results show that the end of the columnar region is abbreviated as a result of seven times higher critical cooling rate than that verified for Al-Si alloys.

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Microstructure and Mechanical Properties of Al-12.6%Si Composite Reinforced by Al63Cu25Fe12Quasicrystal

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.182-183.162 ◽

2012 ◽

Vol 182-183 ◽

pp. 162-166

Author(s):

Can Can Li ◽

Hao Ran Geng ◽

Zhen Yuan Li ◽

Hai Ou Qin

Keyword(s):

Mechanical Properties ◽

Chemical Composition ◽

Cooling Rate ◽

Quasicrystalline Phase ◽

Melt Temperature ◽

Microstructure And Mechanical Properties

In this paper, Al-12.6%Si/Al63Cu25Fe12 composites were fabricated by method of casting. The microstructure and chemical composition of Al63Cu25Fe12 quasicrystal alloy and Al-12.6%Si alloy reinforced by the quasicrystal were studied, and the mechanical properties of Al-12.6%Si composite were also measured. The results show that almost single quasicrystalline phases exist in the samples which are cast with the 1300°C melt. Quickly enough cooling rate and appropriate melt temperature are necessary for the formation of the quasicrystalline phase. In addition, Al-12.6%Si composite has optimal mechanical properties when the amount of Al63Cu25Fe12 quasicrystal is 3 wt%.

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Crack Tip Growth Rate Model for Cyclic Loading

Modelling Problems in Crack Tip Mechanics ◽

10.1007/978-94-009-6198-2_14 ◽

1984 ◽

pp. 229-237 ◽

Cited By ~ 1

Author(s):

F. Ellyin ◽

C. O. A. Fakinlede

Keyword(s):

Growth Rate ◽

Cyclic Loading ◽

Tip Growth ◽

Crack Tip ◽

Rate Model

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Investigation of the Effect of Homogenization Practice of 6063 Alloy Billets on Beta to Alpha Transformation and of the Effect of Cooling Rate on Precipitation Kinetics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.884 ◽

2018 ◽

Vol 941 ◽

pp. 884-889 ◽

Cited By ~ 1

Author(s):

Marianna Katsivarda ◽

Athanasios Vazdirvanidis ◽

George Pantazopoulos ◽

Nikos Kolioubas ◽

Sofia Papadopoulou ◽

...

Keyword(s):

Aspect Ratio ◽

Cooling Rate ◽

Low Cost ◽

Scanning Calorimetry ◽

Joint Research ◽

Intermetallic Particles ◽

Joint Research Project ◽

Mean Diameter ◽

Size And Morphology ◽

Temperature Time

A joint research project was accomplished with the aim to determine the effect of homogenization conditions (temperature, time, cooling rate) on the microstructure and hardness of 6063 alloy billets. Homogenization is crucial for the ability to extrude the piece in low cost, but mainly without defects. Thus, it is of importance to determine the most suitable homogenization conditions (temperature, time, cooling rate) and its effect on both microstructure and hardness of 6063 alloy billets. Furthermore, the size and morphology of the AlFeMnSi intermetallic particles (mean diameter, aspect ratio) and the precipitation behavior of Mg2Si constituents are examined in detail via optical (OM) and scanning electron microscopy (SEM). The resulting mean diameter and aspect ratio data generated by such measurements using OM and image analysis of the intermetallics, that are relevant to the extent of beta-to-alpha transformation, are statistically processed with “ANOVA”. Differential Scanning Calorimetry (DSC) tests are used to determine the coherency level of the particles that were precipitated during the different cooling rates and to reveal the potential for resolutioning the precipitates during billet preheating. Samples received from the plant are compared to laboratory samples in order to facilitate the process of optimization the thermal treatment and improve extrudability.

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Effects of Melt Treatment on Dendrite Coherency of A357 Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3886 ◽

2011 ◽

Vol 189-193 ◽

pp. 3886-3890

Author(s):

Zhong Wei Chen ◽

Pei Chen ◽

Li Fan

Keyword(s):

Thermal Analysis ◽

Growth Rate ◽

Cooling Rate ◽

Solid Fraction ◽

Dendrite Growth ◽

A357 Alloy ◽

Dendrite Coherency Point ◽

Melt Treatment ◽

Coherency Point ◽

Dendrite Coherency

The Dendrite Coherency Point (DCP) of A357 alloy was determined after different melt treatments by double thermocouples, and the coherency solid fraction (fscoh) was calculated by thermal analysis. The results of dendrite coherency properties show that fscoh values increase with increased cooling rate for A357 alloy. For A357 alloys, fscoh values increase after grain refined and melt superheat treatment. The coherency point was found to be dependent on not only the morphology of the dendrites but also the dendrite growth rate.

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