Effect of growth rates and temperature gradients on the lamellar spacing and the undercooling in the directionally solidified Pb–Cd eutectic alloy

2003 ◽  
Vol 38 (9-10) ◽  
pp. 1457-1476 ◽  
Author(s):  
E. Çadırlı ◽  
H. Kaya ◽  
M. Gündüz
Keyword(s):  
Eutectic Alloy ◽  
Growth Rates ◽  
Lamellar Spacing ◽  
Temperature Gradients ◽  
Directionally Solidified

scholarly journals Directional solidification of Zn-Al-Cu eutectic alloy by the vertical Bridgman method

2015 ◽  
Vol 51 (1) ◽  
pp. 67-72 ◽  
Author(s):  
U. Büyük ◽  
S. Engin ◽  
N. Maraşlı
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Temperature Gradient ◽  
Eutectic Alloy ◽  
Temperature Gradients ◽  
Directionally Solidified ◽  
Constant Growth Rate ◽  
Microstructure And Mechanical Properties ◽  
Vertical Bridgman ◽  
Constant Growth

In the present work, the effect of growth rate and temperature gradient on microstructure and mechanical properties of Zn-7wt.%Al-4wt.%Cu eutectic alloy has been investigated. Alloys prepared under steady-state conditions by vacuumed hot filing furnace. Then, the alloys were directionally solidified upward with different growth rates (V=11.62-230.77 mm/s) at a constant temperature gradient (G=7.17 K/mm) and with different temperature gradients (G=7.17-11.04 K/mm) at a constant growth rate (V=11.62 mm/s) by a Bridgman furnace. The microstructures were observed to be lamellae of Zn, Al and broken lamellae CuZn4 phases from quenched samples. The values of eutectic spacing, microhardness and ultimate tensile strength of alloys were measured. The dependency of the microstructure and mechanical properties on growth rate and temperature gradient were investigated using regression analysis.

scholarly journals Columnar-to-Equiaxed Transition in Metal-Matrix Composites Reinforced with Silicon Carbide Particles

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Alicia E. Ares ◽  
Carlos E. Schvezov
Keyword(s):  
Silicon Carbide ◽  
Aluminum Matrix ◽  
Temperature Gradients ◽  
Heat Extraction ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Directionally Solidified ◽  
Alloy Matrix ◽  
Local Conditions ◽  
Ceramic Particles

The present work is focused on the study of the effect of directional heat extraction on the silicon-carbide (SiC) distribution in zinc-aluminum matrix composites (MMCs) and on the columnar-to-equiaxed (CET) position in directionally solidified samples. To this end, a ZA-27 alloy matrix was reinforced with ceramic particles of SiC and vertically directionally solidified. The cooling rates, temperature gradients, and interphase velocities were then measured, and their influence on the solidification microstructure of the MMCs was analyzed. The recalescence detected and measured during the equiaxed transition was of the order of 3.5°C to 1.1°C. The values of the temperature gradients reached a minimum during the CET and were even negative in most cases (between −3.89 K and 0.06 K). The interphase velocities varied between 0.07 mm/s and 0.44 mm/s at the transition. Also, the presence of ceramic particles in ZA-27 alloys affected the thermodynamic local conditions and the kinetics of nucleation, producing a finer microstructure.

Microstructure of Sodium or Potassium Added Mg-Ni Eutectic Alloy

2014 ◽  
Vol 353 ◽  
pp. 228-232
Author(s):  
Hideyuki Saitoh ◽  
Y. Shiraishi
Keyword(s):  
Eutectic Alloy ◽  
Lamellar Spacing ◽  
Eutectic Structure ◽  
Water Quenching ◽  
Rapid Cooling ◽  
Cooling Speed ◽  
Sodium And Potassium ◽  
Refinement Effect ◽  
Potassium Addition

The microstructure of sodium or potassium added Mg-23.5 mass%Ni eutectic alloy was observed and the effect of sodium and potassium addition on the eutectic structure was investigated. All alloys showed the eutectic structure which composed of Mg phase and Mg2Ni phase, and no evidence of the sodium or potassium precipitation occurred. For the sodium added and furnace cooled alloy, the lamellar spacing in the eutectic structure became a little narrow and the Mg2Ni phase tends to become fragmentary as the amount of sodium increases. The sodium addition has a little effect for the refinement of the eutectic structure. For the potassium added and furnace cooled alloy, the lamellar spacing of the eutectic structure became clearly narrow even by the 0.1 mass% potassium additions. The morphology drastically varied in more than 0.5 mass% potassium added specimens, that is, the refinement and fragmentation of the Mg2Ni phase occurred. The potassium addition has a large effect for the refinement and the fragmentation of the Mg2Ni phase in the eutectic structure. For the water quenched specimens, the eutectic structure was extremely fine and globular shape with and without the additive element. The refinement effect by the water quenching is remarkably high even as the non-added specimen. The effect of sodium and potassium addition on the refinement of eutectic structure is not clear in the case of the rapid cooling speed during solidification.

Sign in / Sign up

Export Citation Format

Share Document