scholarly journals Orientation and Microstructure Evolution of Al-Al2Cu Regular Eutectic Lamellar Bifurcating in an Abruptly Changing Velocity under Directional Solidification

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1004
Author(s):  
Ka Gao ◽  
Zan Zhang ◽  
Junliang Zhao ◽  
Dejian Sun ◽  
Fu Wang
Keyword(s):  
Heat Flow ◽  
Directional Solidification ◽  
Flow Direction ◽  
Solidification Rate ◽  
Lateral Diffusion ◽  
Interfacial Instability ◽  
Growth Orientation ◽  
Al2cu Phase ◽  
Heat Flow Direction ◽  
Solidification Microstructures

In an abruptly changing velocity under directional solidification, microstructures and the growth orientation of Al-Al2Cu eutectic lamellar were characterized. The change in solidification rate led to an interfacial instability, which results in a bifurcation of the eutectic lamella into new, refined lamellae. The growth orientation of the eutectic Al2Cu phase was also only in its (001) direction and more strongly oriented to the heat flow direction. The results suggest that the eutectic lamellar Al-Al2Cu bifurcation and the spacing adjustment may be caused by the rate determining lateral diffusion of the solutes after interfacial instability.

scholarly journals Influence of heat flow direction on solder ball interfacial layer

2018 ◽  
Vol 69 (4) ◽  
pp. 305-310 ◽  
Author(s):  
Alexandr Otáhal ◽  
Ivan Szendiuch
Keyword(s):  
Heat Flow ◽  
Flow Direction ◽  
Intermetallic Layer ◽  
Point Of View ◽  
Infrared Heating ◽  
Root Mean Square Roughness ◽  
Sac305 Solder ◽  
Heat Flow Direction ◽  
Solder Balls ◽  
Bga Package

Abstract This paper deals with the research of an intermetallic layer of SAC305 solder balls soldered from three directions of the heat flow in the ball-attach process for BGA package. From the point of view of the heat flow direction, the samples were soldered by infrared heating. The heat sources were placed on the top, bottom and both lateral sides of the BGA package. After the solder balls-attach process, a metallographic cross-section was performed, followed by selective etching to visualize the relief of the intermetallic layer. Images of the interfacial between the solder and solder pad were taken from the created samples, followed by measurement of the average thickness and root mean square roughness of the intermetallic layer. The results showed changes in the intermetallic layer. The largest thickness of the intermetallic layer was observed on samples soldered from the top and both sides. Soldering with the bottom infrared heater resulted to the smallest thickness of the intermetallic layer. The same trend was in the roughness of the IMC layer. The greatest roughness was found for samples soldered by the top and both side heaters. The top soldered samples exhibit the smallest roughness.

The importance of heat flow direction for reproducible and homogeneous freezing of bulk protein solutions

2013 ◽  
Vol 29 (5) ◽  
pp. 1212-1221 ◽  
Author(s):  
Miguel A. Rodrigues ◽  
Gustavo Balzan ◽  
Mónica Rosa ◽  
Diana Gomes ◽  
Edmundo G. de Azevedo ◽  
...  
Keyword(s):  
Heat Flow ◽  
Flow Direction ◽  
Protein Solutions ◽  
Heat Flow Direction ◽  
Homogeneous Freezing

Multi-phase field simulation of competitive grain growth for directional solidification

2021 ◽  
Author(s):  
Chang-sheng Zhu ◽  
Zi-hao Gao ◽  
Peng Lei ◽  
Li Feng ◽  
Bo-rui Zhao
Keyword(s):  
Heat Flow ◽  
Grain Boundary ◽  
Directional Solidification ◽  
Phase Field ◽  
Flow Direction ◽  
Orientation Angle ◽  
Growth Direction ◽  
Model Alloy ◽  
Competitive Growth ◽  
Multi Phase

Abstract The multi-phase field model of grain competitive growth during directional solidification of alloy was established, solving multi-phase field models for thin interface layer thickness conditions, grain boundary evolution and grain elimination during the competitive growth of SCN-0.24wt% camphor model alloy bi-crystals were investigated, the effects of different crystal orientations and pulling velocities on grain boundary microstructure evolution were quantitatively analyzed. The results show that in the competitive growth of convergent bi-crystals, when favorably oriented dendrites are in the same direction as the heat flow and the pulling speed is too large, the orientation angle of the bi-crystal from small to large is the normal elimination phenomenon of the favorably oriented dendrite blocking the unfavorably oriented dendrite, and the grain boundary is along the growth direction of the favorably oriented dendrite, and when the pulling speed becomes small, the grain boundary shows the anomalous elimination phenomenon of the unfavorably oriented dendrite eliminating the favorably oriented dendrite. In the process of competitive growth of divergent bi-crystal, when the growth direction of favorably oriented dendrites is the same as the heat flow direction and the orientation angle of unfavorably oriented grains is small, the frequency of new spindles of favorably oriented grains is significantly higher than that of unfavorably oriented grains, and as the orientation angle of unfavorably oriented dendrites becomes larger, the unfavorably oriented grains are more likely to have stable secondary dendritic arms, which in turn develop new primary dendritic arms to occupy the liquid phase grain boundary space, but the grain boundary direction is still parallel to favorably oriented dendrites. In addition, the tertiary dendritic arms on the developed secondary dendritic arms may also be blocked by the surrounding lateral branches from further developing into nascent main axes, this blocking of the tertiary dendritic arms has a random nature, which can have an impact on the generation of nascent primary main axes in the grain boundaries.

scholarly journals Analysis of Temperature Field, Heat and Fluid Flow of Two-Phase Zone Continuous Casting Cu–Sn Alloy Wire

2016 ◽  
Vol 16 (1) ◽  
pp. 33-40 ◽  
Author(s):  
J. Luo ◽  
X. Liu ◽  
X. Wang
Keyword(s):  
Temperature Field ◽  
Fluid Flow ◽  
Heat Flow ◽  
Continuous Casting ◽  
Flow Direction ◽  
Phase Zone ◽  
Two Phase ◽  
Alloy Wire ◽  
Heat Flow Direction ◽  
Heat And Fluid Flow

Abstract Cu–4.7 wt. % Sn alloy wire with Ø10 mm was prepared by two-phase zone continuous casting technology, and the temperature field, heat and fluid flow were investigated by the numerical simulated method. As the melting temperature, mold temperature, continuous casting speed and cooling water temperature is 1200 °C, 1040 °C, 20 mm/min and 18 °C, respectively, the alloy temperature in the mold is in the range of 720 °C–1081 °C, and the solid/liquid interface is in the mold. In the center of the mold, the heat flow direction is vertically downward. At the upper wall of the mold, the heat flow direction is obliquely downward and deflects toward the mold, and at the lower wall of the mold, the heat flow deflects toward the alloy. There is a complex circular flow in the mold. Liquid alloy flows downward along the wall of the mold and flows upward in the center.

Thermoelectric Power of Gradient Fex(Al2O3)100-x Composite Films

2015 ◽  
Vol 233-234 ◽  
pp. 694-698 ◽  
Author(s):  
Oleg Stognei ◽  
Ahmed Al-Maliki ◽  
Alexander Sitnikov ◽  
Vladimir Makagonov
Keyword(s):  
Heat Flow ◽  
Temperature Gradient ◽  
Thermoelectric Power ◽  
Concentration Gradient ◽  
Flow Direction ◽  
Composite Films ◽  
Sputter Deposition ◽  
Deposition Technique ◽  
Opposite Edge ◽  
Heat Flow Direction

Nanocomposite Fex(Al2O3)100-x films with concentration gradient along the long axis of the samples (40 mm) have been obtained by sputter deposition technique and investigated. Based on the electric and magnetoresistive investigations the gradient Fex(Al2O3)100-x samples in which concentration of one edge of the sample is smaller than concentration of a percolation threshold while concentration of opposite edge of this sample is upper the threshold have been determined. Influence of the heat flow direction on the thermoelectric power of the gradient samples has been investigated. Hysteresis of the thermoelectric power is observed when temperature gradient direction is changed.

scholarly journals Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7772
Author(s):  
Hamed H. Saber ◽  
David W. Yarbrough
Keyword(s):  
Heat Flow ◽  
Aspect Ratio ◽  
Thermal Resistance ◽  
Flow Direction ◽  
Total Heat Transfer ◽  
Temperature Variations ◽  
One Dimensional ◽  
Heat Flow Direction ◽  
R Value ◽  
The Impact

Enclosed airspaces to reduce heat flow have been recognized for well over 100 years. Airspaces with one or more reflective surfaces define reflective insulation (RI) assemblies, a product type used in walls, roofs, windows with multiple panes, curtain walls and skylights. The thermal resistance (R value) of airspaces depends on the emittance of all surfaces, airspace dimensions and orientation, heat flow direction and surfaces temperatures. The modeling of RI now includes CFD coupled with radiation to quantify the total heat transfer. This study compares a validated model for airspace R values with existing methods such as ISO 6946 and hot-box results that provide the R values in the ASHRAE Handbook of Fundamentals. The existing methods do not include an airspace aspect ratio. This study showed that the aspect ratio can impact the R value by a factor of two. The impact of aspect ratio was calculated for double airspaces variation such as that for single airspaces. The present calculations are two-dimensional and also consider all the bounding airspace surfaces, while previous methods are one-dimensional and do not include surface temperature variations or detailed radiative transport.

Sign in / Sign up

Export Citation Format

Share Document