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Postgraduate Projects
Postgraduate
students play a significant role in CAST's strategic research and
add considerable value to our research program. A description of
postgraduate research in each sector follows (click to see full
listing of postgraduate
projects).
Aluminium Casthouse Products
Xiangdong Yao continues research into
the mathematical modelling of hypoeutectic alloy microstructure
evolution during solidification (both primary phase and eutectic)
in an effort to simulate the development of as-cast microstructure.
Stuart McDonald completed his
research into understanding the role of strontium on eutectic growth
mode and the formation of porosity in Al-Si-Cu casting alloys. This
research helps us to understand how to control casting conditions
and alloy composition to achieve defect free cast structures.
Kiho Rhee is conducting research
into the rolling response of heat treated 6000 series aluminium
alloy sheet by varying material orientation during use of the Equal
Channel Angular Extrusion (ECAE) technique. Contributions towards
the optimisation of rolling and heat treatment cycles for the production
of highly formable 6000 series automotive sheet should be possible
using continuation of the ECAE technique.
Ian Bainbridge continues his
research into the characterisation of surface defects in air-pressurised
VDC cast billet and has proposed some new hypotheses for testing.
An experimental program into surface tension effects and mould-metal
thermal interactions will add to our understanding of surface formation
and control in VDC billet casting and reduce the formation of surface
defects.
A new CAST postgraduate project on hot tearing
of aluminium alloys has recently been started by David Viano and
involves collaboration with SINTEF's modelling and simulation group
in Norway.
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Aluminium Die Casting
Cameron Dinnis is undertaking a PhD on, "The
Effect of Manganese on the Feedability of Alloy 380", an aluminium
alloy that is commonly used in the manufacture of engine blocks.
A mechanism for the effect of manganese on porosity formation has
been proposed and castings are now being made to test this mechanism.
During this year Cameron won a University of Queensland Graduate
School Research Travel Award, which he intends to use to undertake
research at VAW in Germany who are a sponsor of his PhD studies.
Matthew Patrzalek's cycle time
reduction project is developing well with the experimental rig up
and running, incorporating minor modifications to increase safety
and reduce timing delays. Future work will focus on the completion
of experimental trial runs on the rig. This will lead to the development
of a database of the temperature profile (both experimentally and
numerically) within the experimental die for a variety of operating
conditions.
Suresh Palanisamy's PhD thesis
on the "Ultrasonic Inspection of Sub-surface Defects in Aluminium
Die Castings" has verified the reliability of the ultrasound
immersion testing experimental set-up used in the project. Suresh
is carrying out surface profile measurement to find the loss of
ultrasound signal on the rough surfaces of sample castings and has
also started neural network implementation work for classification
of defect signals. The project has also validated the viability
of inspecting Aluminium die castings to detect porosity using ultrasonic
techniques.
Imad Khan has recently begun
a PhD thesis on, "Development of an implementation strategy
for cycle time control" and will be working in close conjunction
with CAST's partners Ford and Nissan. Michael Roberts' Masters thesis
on the "Manufacturing Life Cycle Analysis of Cast Products"
has resulted in the collection of a Life Cycle Inventory (LCI) of
Aluminium High Pressure Die Casting. This inventory is currently
being incorporated into the Total Cost Model of Aluminium High Pressure
Die Casting.
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Magnesium Production
John Grandfield was awarded a PhD for his work
on modelling of the horizontal direct chill (HDC) process for magnesium.
Young Lee has submitted his
thesis on grain refinement of magnesium alloys and this is awaiting
the results of examination.
A new student, Chris Corby,
has recently started a project examining the formation of Fe-Mn-Al
intermetallic particles in magnesium alloys. Manganese is added
to Mg-Al die casting alloys to precipitate iron but the existing
process produces only small intermetallic particles. It is hoped
to be able to grow and study larger particles with the aim of optimising
the intermetallic formation temperature and the level of Mn required.
The knowledge developed may allow the cost of the production of
the common die casting alloys to be reduced while also improving
their quality.
An undergraduate project by
Elizabeth Webber is continuing on the replacement of beryllium in
die casting alloys with something more environmentally friendly.
Beryllium is added to magnesium die casting alloys to assist in
oxidation prevention. However, beryllium fumes and dusts are known
to be complicit in one form of lung disease. Preliminary results
are encouraging and could result in development of a much larger
project.
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Magnesium Applications
Postgraduate research projects serve both
an educational function and provide a means of investigating areas
at a level of depth greater than is possible in the more commercially
orientated core research projects. Consequently, postgraduate and
core research projects are highly complementary.
Mark Nave has recently had his thesis on "Solidification Processes
of Mg-Al Alloys" accepted and has gone on to take up a position
as a research engineer at Deakin University.
In the area of wrought magnesium applications Aiden Beer continues
his thesis on the "Influence of Processing Conditions on the
Formability of Magnesium". Aiden's research is aimed at determining
the optimum conditions for workability of magnesium alloys that
may lead to significant cost savings in the manufacture of magnesium
structures. The insights of this work are of considerable assistance
to the "Production and Processing of Wrought Magnesium Alloys"
Project.
Contributing to CAST's research effort on magnesium corrosion, Jimmy
Jia is undertaking a thesis on, "Computer Modeling and Prevention
of Galvanic Corrosion of Magnesium Alloys", research that will
evaluate methods of preventing corrosion of magnesium components.
Zhiming Shi is researching the influence of microstructure of the
substrate on the corrosion performance of coatings used to protect
Mg alloys in his thesis titled, "Effects of Casting Substrate
on Corrosion Performance of Coatings on Magnesium alloys".
As part of the extensive research program on alloy development (focussed
on alloys for elevated temperature applications) Chamini Mendis
has been looking at the effects of adding Ca to Mg alloys during
her research on the thesis topic, "Effects of Ca Additions
on Microstructures and Creep Behaviour of Mg-Zn-Al Casting Alloys."
The addition of Ca is believed to influence the creep behaviour
of Mg-Zn-Al alloys, however this proposition has never been rigorously
tested. Robert Wilson is undertaking research on, "Microstructure/Mechanical
Property Relationships in Creep-Resistant Mg-Nd-Zn Alloys".
The role of rare earths is a key factor in understanding the performance
of magnesium alloys at elevated temperatures.
The objective of Meity Mandagie's thesis on, "Laser Cladding
of Metal Matrix Composites on Mg Base Alloys to Improve Wear Properties",
is to assess the use of metal matrix composites (MMC) such as oxides
and carbides in a metal matrix to improve the wear properties of
Mg alloy surfaces. This project is a component of CAST's efforts
to develop protective coatings for magnesium alloys.
Several research students have projects on the properties of magnesium
castings. Amanda Bowles is nearing completion of her thesis on the
"Effect of Ageing on Mechanical Properties of High Pressure
Die Casting (HPDC)". Amanda's research has involved determining
the effect of temperature of the tensile properties and microstructure
of high pressure die castings of two commonly used magnesium alloys,
AZ91 and AM60, which in turn will shed light on the usefulness of
such cast products in the automotive industry.
A PhD thesis on the "Low strain behaviour of Mg casting alloys,"
has recently been started by Gemma Miflin. The aim of Gemma's research
is to understand the physical properties of magnesium sand cast
alloys, in particular, the influence of zirconium grain refinement
on the behaviour of Mg-Zn alloy.
The mechanical properties of increasingly popular high pressure
die castings (HPDC) of magnesium are being investigated by Chris
Pitsaris in his thesis, "Properties of Mg High Pressure Die
Castings". The results of this research should assist designers
interested in incorporating Mg alloys as components in a range of
applications.
Improving our understanding of the behaviour of Mg-Al alloys is
the object of Taro Sumitomo's PhD research on, "Tensile and
Fracture Behaviour of HPDC and Sand-Cast Mg-Al Alloys". The
results of this research will be a set of data and equations that
can be used to model the behaviour of Mg alloys under different
physical conditions.
Caixian Tang's research project on, "Development of Coatings
for Prevention of Soldering of Magnesium Alloys" is also focused
on magnesium castings and is investigating interactions of molten
metal with steel dies. This research could lead to improvements
in die lifetimes.
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