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 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.

Particle-Stimulated Nucleation of Recrystallization for Grain-Size Control in 01420 Al-Li Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 889-892 ◽  
Author(s):  
Ling Ying Ye ◽  
Xin Ming Zhang ◽  
Yu Xuan Du ◽  
Zhi Hui Luo
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Size Control ◽  
S Phase ◽  
Second Phase ◽  
Β Phase ◽  
Nucleation Sites ◽  
Second Phase Particles ◽  
Average Grain Size ◽  
Grain Size Control

Grain refinement of 01420 Al-Li alloy through particle stimulated nucleation(PSN) of recrystallization is reported. The results showed that the rolling in the overaged 01420 Al-Li alloy resulted in the formation of the deformation zones associated with the second phase particles larger than 0.80 μm which can act as the nucleation sites for recrystallized grains. The precipitates larger than 0.80 μm are sticked shaped S-phase(Al2MgLi) and globular β-phase(Mg2Al3), and the density of β-phase particles is approximately as two to three times as the S-phase particles. The S-phase particles can’t be as PSN sites since they were broken to small dispersoid particles during rolling. The average grain size of 01420 Al-Li alloy solutioned at 470°C for 2h, aged at 300 °C for 48h, 81% rolled at 300 °C and finally recrystallized at 500 °C for 10min is approximately 10 μm.

Grain size control in Al–Si alloys by grain refinement and electromagnetic stirring

2009 ◽  
Vol 487 (1-2) ◽  
pp. 163-172 ◽  
Author(s):  
V. Metan ◽  
K. Eigenfeld ◽  
D. Räbiger ◽  
M. Leonhardt ◽  
S. Eckert
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Size Control ◽  
Electromagnetic Stirring ◽  
Grain Size Control

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 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.

Interfacial studies in Nb3Sn superconductors

1991 ◽  
Vol 49 ◽  
pp. 590-591
Author(s):  
Ernest L. Hall ◽  
Lee E. Rumaner ◽  
Mark G. Benz
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Flux Pinning ◽  
Size Control ◽  
High Magnetic Fields ◽  
Type Ii ◽  
Reaction Interface ◽  
Liquid Diffusion ◽  
Type Ii Superconductor ◽  
Grain Size Control

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

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