Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Substantial undercooling brings about microstructural change for ternary eutectic alloy

11.02.2009
The Department of Applied Physics, Northwestern Polytechnical University (NPU) in Xi'an, China-Research, has shown that the substantial undercooling of liquid state brings about novel microstructural transition for Al-Cu-Si ternary eutectic alloy. The study is reported in Issue 54 (January, 2009) of Chinese Science Bulletin because of its significant research value.

Al¡VCu¡VSi alloy is widely applied in industry mainly as a light construction material. It is also a promising material for applications such as engine block and cylinder heads. It is important for designers to have an intimate knowledge of how Al¡VCu-Si alloy solidifies because its mechanical performance is usually controlled by solidification mechanism and microstructural characteristics. However, so far there has been little research on its rapid solidification mechanism under the extremely nonequilibrium condition.

In this work, Al80.4Cu13.6Si6 eutectic alloy was undercooled up to 147 K (0.18TE). Generally speaking, under the conventional solidification condition, a liquid aluminium alloy can be hardly undercooled because of oxidation. Dr. Ruan and Prof. Wei made it realized by choosing dehydrated B2O3 agent as a denucleating agent and providing a high-vacuum environment and special melting processing. In addition, the experimental parameters, such as cooling rate, superheating, and holding time, were controlled in order to get a wider undercooling range for comparison.

The undercooling level of alloy melt has a strong effect on its crystallization kinetics, structure morphology, and final physical and chemical properties. This study presents the microstructural characteristics of highly undercooled Al80.4Cu13.6Si6 ternary eutectic alloys. So far, most investigations on eutectic growth focus on binary alloy systems. The rapid solidification of undercooled ternary alloys involves the competitive nucleation and coupled growth of three eutectic phases from one liquid phase, which makes it more complicated than the case of binary alloys. The authors showed that the phase selection of Al80.4Cu13.6Si6 ternary eutectic alloy is influenced by undercooling, which makes the competitive nucleation and cooperative growth among Ą(Al), (Si) and ć(CuAl2) phases become more drastic. Once undercooling exceeds 73 K, the primary phase will transform from (Al) dendrite to faceted (Si) block.

"This paper emphasizes the phase selection and microstructure formation of substantially undercooled ternary eutectic alloys. The result is of academic and practical significance." said one journal reviewer. A series of papers about rapid solidification of ternary eutectic alloys written by Dr. Ruan and Prof. Wei have been published in Chin. Sci. Bull., Sci. Chin. G, etc. "It enriched and expanded the research results on nonequilibrium solidification. It offered us new references to develop solidification and nonequilibrium phase transition theory," said another reviewer.

The authors are affiliated at Laboratory of Space Materials Science and Technology (LMSS) of NPU. This laboratory is conducting research mainly in three respects: materials processing under the space simulation condition, thermophysical properties of undercooled liquid alloys, and computational material science.

Y Ruan, B Wei | EurekAlert!
Further information:
http://www.nwpu.edu.cn

More articles from Physics and Astronomy:

nachricht Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>