scholarly journals Cooling curve analysis in binary Al-Cu alloys: Part II- Effect of Cooling Rate and Grain Refinement on The Thermal and Thermodynamic Characteristics

10.30544/81 ◽  
2015 ◽  
Vol 21 (3) ◽  
pp. 207-222 ◽  
Author(s):  
Mehdi Dehnavi ◽  
Mohsen Haddad-Sabzevar ◽  
Mohamad Hasan Avazkonnadeh-Gharavol
Keyword(s):  
Cooling Rate ◽  
Grain Refinement ◽  
Latent Heat ◽  
Thermodynamic Characteristics ◽  
Curve Analysis ◽  
Cooling Curve ◽  
Cu Alloys ◽  
Master Alloys ◽  
Cooling Curve Analysis ◽  
Casting Industry

The Al-Cu alloys have been widely used in aerospace, automobile, and airplane applications. Generally Al–Ti and Al–Ti–B master alloys are added to the aluminium alloys for grain refinement. The cooling curve analysis (CCA) has been used extensively in metal casting industry to predict microstructure constituents, grain refinement and to calculate the latent heat of solidification. The aim of this study is to investigate the effect of cooling rate and grain refinement on the thermal and thermodynamic characteristics of Al-Cu alloys by cooling curve analysis. To do this, Al-Cu alloys containing 3.7, and 4.8 wt.% Cu were melted and solidified with 0.04, 0.19, 0.42, and 1.08 K/s cooling rates. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. Some samples were Grain refined by Al-5Ti-1B to see the effect of grain refinement on the aforementioned properties. The results show that, in a well refined alloy, nucleation will occur in a shorter time, and a undercooling approximately decreases to zero. The other results show that, with considering the cooling rate being around 0.1 °C/s, the Newtonian method is efficient in calculating the latent heat of solidification.

scholarly journals Grain size control in al-4.8 wt.% Cu alloy by computeraided cooling curve analysis

2014 ◽  
Vol 20 (3) ◽  
pp. 183-190
Author(s):  
Mehdi Dehnavi ◽  
Mohsen Haddad Sabzevar
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Size Control ◽  
Curve Analysis ◽  
Cooling Curve ◽  
Cu Alloy ◽  
Master Alloys ◽  
Cooling Curve Analysis ◽  
Grain Size Control ◽  
Casting Industry

Generally Al–Ti and Al–Ti–B master alloys are added to the aluminium alloys for grain refinement. The cooling curve analysis (CCA) has been used extensively in metal casting industry to predict microstructure constituents, grain refinement and to calculate the latent heat of solidification. The aim of this study was to investigate the effect of grain refinement on the grain size of Al-4.8 wt.%Cu alloy by cooling curve analysis. To do this, alloy was grain refined by different amount of Al-5Ti-1B master alloy and all samples were solidified at constant cooling rate of 0.19 ℃/s. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. The results show that the segregating power of Ti is very high and it segregates to the nucleant–liquid interface which leads to constitutional supercooling within which other nucleant particles get activated for nucleation. Other results show that with considering the changes in the primary undercooling (ΔTRU) as the main factor to determine the effectiveness of grain refinement process, it was found that by grain refinement, the value of undercooling decrease was approximately zero. 

scholarly journals Cooling curve analysis in binary Al-Cu alloys: Part I- Effect of cooling rate and copper content on the eutectic formation

10.30544/80 ◽  
2015 ◽  
Vol 21 (3) ◽  
pp. 195-206 ◽  
Author(s):  
M. Dehnavi ◽  
F. Kuhestani ◽  
M. Haddad-Sabzevar
Keyword(s):  
Cooling Rate ◽  
Latent Heat ◽  
Copper Content ◽  
Time Derivative ◽  
Weight Percent ◽  
Curve Analysis ◽  
Cooling Curve ◽  
Copper Addition ◽  
Cooling Curve Analysis ◽  
First Time

There are many techniques available for investigating the solidification of metals and alloys. In recent years computer-aided cooling curve analysis (CA-CCA) has been used to determine thermo-physical properties of alloys, latent heat and solid fraction. In this study, the effect of cooling rate and copper addition was taken into consideration in non- equilibrium eutectic transformation of binary Al- Cu melt via cooling curve analysis. For this purpose, melts with different copper weight percent of 2.2, 3.7 and 4.8 were prepared and cooled in controlled rates of 0.04 and 0.42 °C/s. Results show that, latent heat of alloy highly depends upon the post- solidification cooling rate and composition. As copper content of alloy and cooling rate increase, achieved nonequilibrium eutectic phase increases that leads to release of high amount of latent heat and appearing of second deviation in cooling curve. This deviation can be seen in first time derivative curve in the form of a definite peak.

scholarly journals Comparison of Newtonian and Fourier thermal analysis techniques for calculation of latent heat and solid fraction of aluminum alloys

10.30544/379 ◽  
2004 ◽  
Vol 10 (2) ◽  
pp. 91-106 ◽  
Author(s):  
DARYOUSH EMADI ◽  
LAURENCE V. WHITING ◽  
MILE DJURDJEVIC ◽  
WITOLD T. KIERKUS ◽  
JERRY SOKOLOWSKI
Keyword(s):  
Latent Heat ◽  
Solid Fraction ◽  
Curve Analysis ◽  
Cooling Curve ◽  
Fourier Thermal Analysis ◽  
Liquid Phases ◽  
Cooling Curve Analysis ◽  
Curve Determination ◽  
Casting Industry ◽  
Thermal Analysis Techniques

The cooling curve analysis (CCA) has been used extensively in the metal casting industry, usually to predict alloy compositio n and microstructure constituents. The use of CCA can be expanded to other areas of solidification if the zero curves can be properly calculated. In this paper the Newtonian and Fourier techniques of zero curve determination are described. These techniques were developed to calculate latent heat and to determine the correlations between solid fraction and temperature/time for Al-7 wt%Si alloy. The importance of the changes in heat capacity and density of solid and liquid phases during solidification on the latent heat calculations was examined. The latent heat calculated by Computer-Aided Cooling Curve Analysis (CA-CCA) method is compared with those reported in the literature. The effect of experimental procedure and type of sampling cup on the latent heat calculations were studied for both techniques.

Determination of the latent heat of fusion and solid fraction evolution of metals and alloys by an improved cooling curve analysis method

2019 ◽  
Vol 140 (4) ◽  
pp. 1825-1836 ◽  
Author(s):  
Carlos González-Rivera ◽  
Anthony Harrup ◽  
Carla Aguilar ◽  
Adrián M. Amaro-Villeda ◽  
Marco A. Ramírez-Argáez
Keyword(s):  
Latent Heat ◽  
Solid Fraction ◽  
Metals And Alloys ◽  
Curve Analysis ◽  
Cooling Curve ◽  
Heat Of Fusion ◽  
Analysis Method ◽  
Latent Heat Of Fusion ◽  
Cooling Curve Analysis

scholarly journals Cooling Curve Analysis Method using a Simplified Energy Balance

2018 ◽  
Vol 3 (1) ◽  
pp. 383
Author(s):  
C. González Rivera ◽  
A. Amaro Villeda ◽  
M. Ramírez Argáez
Keyword(s):  
Energy Balance ◽  
Latent Heat ◽  
Curve Analysis ◽  
Phase Changes ◽  
Cooling Curve ◽  
Analysis Method ◽  
Cooling Process ◽  
Solidification Kinetics ◽  
Cooling Curve Analysis ◽  
Metallic Sample

In this work is described a new cooling curve analysis method focused on the experimental determination of the latent heat of phase changes and phase transformation kinetics.The method analyses the cooling process of a metallic sample, initially liquid that is contained into a cylindrical metallic mold, both of known weight, thermally isolated at its top and bottom. The method is based on a simplified energy balance associated with the experimental measurement of the temperature change of the sample during its cooling process. The method was applied experimentally to zinc and tin of commercial purity, initially liquids and contained into stainless steel molds in order to determine its ability to determine the latent heat of solidification. In order to validate the method, the obtained values of latent heat were compared with the values reported in thermochemical databases. The obtained results suggest that this method can be used to characterize the solidification of metals..Keywords: Solidification, Kinetics; Cooling curve analysis.

scholarly journals Investigation the solidification of Al-4.8 wt.%Cu alloy at different cooling rate by computer-aided cooling curve analysis

2014 ◽  
Vol 20 (2) ◽  
pp. 107-118 ◽  
Author(s):  
Mehdi Dehnavi ◽  
Hosein Vafaeenezhad ◽  
Mohsen Haddad Sabzevar
Keyword(s):  
Cooling Rate ◽  
Alloy Composition ◽  
Data Acquisition System ◽  
Structural Features ◽  
Curve Analysis ◽  
Cooling Curve ◽  
Cooling Curves ◽  
Cu Alloy ◽  
Cooling Curve Analysis ◽  
Computer Aided

Depending on the casting conditions and alloy composition, microstructure and properties of the aluminium alloys will be different. There are many techniques available for investigating the solidification of metals and alloys. In recent years computer-aided cooling curve analysis (CA-CCA) has been used to determine thermophysical properties of alloys, latent heat and solid fraction. The aim of this study was to investigate the effect of cooling rate on the structural features of Al-4.8 wt.%Cu alloy by thermal analysis of cooling curves. To do this, Al-4.8 wt.%Cu alloy was melted and solidified applying 0.04, 0.42, and 1.08 °C/sec cooling rates. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. It was found that the formation temperatures of various thermal parameters such as (liquidus, solidus and eutectic temperatures) are shifting by increasing of cooling rate from 0.04 °C/sec to 1.08 °C/sec. The structural results show that grain size and secondary dendrite arm spacing decreased by increasing of cooling rate. 

scholarly journals Impact of major alloying elements on the solodification parameters of cast hypoeutectic AlSi6Cu (1–4 wt.%) and AlSi8Cu(1−4 wt.%) alloys

2014 ◽  
Vol 20 (4) ◽  
pp. 235-246 ◽  
Author(s):  
Mile B. Djurdjević ◽  
Srećko Manasijević
Keyword(s):  
Curve Analysis ◽  
Cooling Curve ◽  
Freezing Range ◽  
Cooling Curves ◽  
First Derivative ◽  
Cu Alloys ◽  
Fraction Solid ◽  
Analysis Technique ◽  
Cooling Curve Analysis ◽  
Crack Susceptibility

The present work displays the potential of cooling curve analysis to characterize the solidification path of cast hypoeutectic series of Al-Si6-Cu(1−4 wt.%) and Al-Si8- Cu(1−4 wt.%) alloys. The aim of this work was to examine how variation in chemical composition of silicon and copper may affect characteristic solidification temperatures, fraction solid, and thermal freezing range of investigated alloys. Eight different Al−Si−Cu alloys (Al-Si6-Cu1, Al-Si6-Cu2, Al-Si6-Cu3, Al-Si6-Cu4, Al-Si8-Cu1, AlSi8-Cu2, Al-Si8-Cu3 and Al-Si8-Cu4) have been analyzed applying cooling curve analysis technique. Characteristic solidification temperatures have been determined using cooling curves or their corresponding first derivative curves along with ΔT curves. Fraction solid curves determined from recorded cooling curves have been used to calculate terminal freezing range and estimate crack susceptibility coefficient for each alloy. Theoretical mode for prediction of the cracking susceptibility coefficient developed by Clyne and Davies has been considered in this work. In addition, a novel mathematical model for prediction of crack susceptibility coefficient based on data collected from cooling curve analysis has been proposed. 

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