Chapter 16
Study of a Semisolid Processing Route for Producing
an AlSiMg0.5Mn Matrix Syntactic Foam via Thixoinfiltration
of Fly Ash Micro Balloons
R. C. Moraes, J. P. Paschoal, E. Bayraktar, R. Silva, R. Costa, and F. Gatamorta
Abstract Metal matrix composites are widely used in modern engineering as a result of the needing for distinct features into
the same material, and for presenting such characteristics, the metallic foams have been increasingly used mainly from the
mobility industry. Therefore a semisolid processing route for producing an AlSiMg0.5Mn matrix syntactic foam was
idealized, by the thixoinfiltration of an industrial waste known as fly ash micro balloons. Preliminary a thorough study of
the balloons morphology and chemical composition had been done, as also the AlMg2.5 thixoability through Spectrometry,
Differential Scanning Calorimetry (DSC). The process parameters were defined to obtain a homogeneous pore distribution
into the matrix and good wettability of balloons analyzed by x-ray micro tomography (Micro CT) and optical microscopy.
16.1 Introduction
Throughout the history of society, continuous technological development is necessary as a way to face the challenges that
human evolution itself imposes. One of the main areas related to this advance is the design and improvement of materials and
alloys, since the emergence of new technologies and applications results in the need to improve material resources, such as
increased mechanical strength, resistance to high temperatures, weight reduction, better resistance in harmful environments,
among other properties.
As metallic foams are a new class of materials that have arisen due to these requirements, they may include characteristics
of a material with less density, and innovative chemical, mechanical, thermal, electrical and acoustic proprieties. Metallic
foams, also known as cellular metals, are generally characterized by a large volume fraction of the porosity, sometimes
reaching levels above 80% [1]. A subgroup of the metal foams class is like synthetic metallic foams, which consists of the
addition of hollow ceramic particles in a metallic matrix.
As an example of the production of syntactic metallic foams, we can mention the method called Stir Casting, where a high
shear impeller is used to mix and homogenize solid particles in a molten alloy [2]. Another of these techniques is called
Pressure Infiltration, where the molten metal is forced into a mold with the assistance of a high pressure and/or vacuum, whose
interior is formed by a preform or bed of hollow and free particles [3]. These foams can also be produced via Powder
Metallurgy, with hollow particles and metallic powder mixed, compacted and sintered [4].
In this work, a syntactic metallic foam design is developed, aiming at reducing density and improving mechanical
properties associated with structural applications. It was produced by adding micro ceramic balloons to an aluminum matrix
by the infiltration process. Thixoforming is a viable technology for the formation of alloys in the semi-solid state for near
net-shape parts. This technique basically consists of three phases: the production of a material with globular microstructure;
heating the material to working temperature and; applying pressure using a press to shape the material [5].
R. C. Moraes · F. Gatamorta
University of Campinas, UNICAMP/FEM-Department of Materials, Campinas, SP, Brazil
e-mail: fabiog@fem.unicamp.br
J. P. Paschoal · R. Silva · R. Costa
Federal University of Technology-Paraná, Campus Cornélio Procópio, UTFPR-CP/PPGEM, Cornélio Procópio, PR, Brazil
e-mail: romeu@utfpr.edu.br
E. Bayraktar (*)
University of Campinas, UNICAMP/FEM-Department of Materials, Campinas, SP, Brazil
Supmeca-Paris, Mechanical and Manufacturing Engineering School, Paris, France
e-mail: bayraktar@supmeca.fr
© The Society for Experimental Mechanics, Inc. 2021
R. P. Singh, V. Chalivendra (eds.), Mechanics of Composite, Hybrid and Multifunctional Materials, Volume 6,
Conference Proceedings of the Society for Experimental Mechanics Series, https://doi.org/10.1007/978-3-030-59868-6_16
107
Study of a Semisolid Processing Route for Producing
an AlSiMg0.5Mn Matrix Syntactic Foam via Thixoinfiltration
of Fly Ash Micro Balloons
R. C. Moraes, J. P. Paschoal, E. Bayraktar, R. Silva, R. Costa, and F. Gatamorta
Abstract Metal matrix composites are widely used in modern engineering as a result of the needing for distinct features into
the same material, and for presenting such characteristics, the metallic foams have been increasingly used mainly from the
mobility industry. Therefore a semisolid processing route for producing an AlSiMg0.5Mn matrix syntactic foam was
idealized, by the thixoinfiltration of an industrial waste known as fly ash micro balloons. Preliminary a thorough study of
the balloons morphology and chemical composition had been done, as also the AlMg2.5 thixoability through Spectrometry,
Differential Scanning Calorimetry (DSC). The process parameters were defined to obtain a homogeneous pore distribution
into the matrix and good wettability of balloons analyzed by x-ray micro tomography (Micro CT) and optical microscopy.
16.1 Introduction
Throughout the history of society, continuous technological development is necessary as a way to face the challenges that
human evolution itself imposes. One of the main areas related to this advance is the design and improvement of materials and
alloys, since the emergence of new technologies and applications results in the need to improve material resources, such as
increased mechanical strength, resistance to high temperatures, weight reduction, better resistance in harmful environments,
among other properties.
As metallic foams are a new class of materials that have arisen due to these requirements, they may include characteristics
of a material with less density, and innovative chemical, mechanical, thermal, electrical and acoustic proprieties. Metallic
foams, also known as cellular metals, are generally characterized by a large volume fraction of the porosity, sometimes
reaching levels above 80% [1]. A subgroup of the metal foams class is like synthetic metallic foams, which consists of the
addition of hollow ceramic particles in a metallic matrix.
As an example of the production of syntactic metallic foams, we can mention the method called Stir Casting, where a high
shear impeller is used to mix and homogenize solid particles in a molten alloy [2]. Another of these techniques is called
Pressure Infiltration, where the molten metal is forced into a mold with the assistance of a high pressure and/or vacuum, whose
interior is formed by a preform or bed of hollow and free particles [3]. These foams can also be produced via Powder
Metallurgy, with hollow particles and metallic powder mixed, compacted and sintered [4].
In this work, a syntactic metallic foam design is developed, aiming at reducing density and improving mechanical
properties associated with structural applications. It was produced by adding micro ceramic balloons to an aluminum matrix
by the infiltration process. Thixoforming is a viable technology for the formation of alloys in the semi-solid state for near
net-shape parts. This technique basically consists of three phases: the production of a material with globular microstructure;
heating the material to working temperature and; applying pressure using a press to shape the material [5].
R. C. Moraes · F. Gatamorta
University of Campinas, UNICAMP/FEM-Department of Materials, Campinas, SP, Brazil
e-mail: fabiog@fem.unicamp.br
J. P. Paschoal · R. Silva · R. Costa
Federal University of Technology-Paraná, Campus Cornélio Procópio, UTFPR-CP/PPGEM, Cornélio Procópio, PR, Brazil
e-mail: romeu@utfpr.edu.br
E. Bayraktar (*)
University of Campinas, UNICAMP/FEM-Department of Materials, Campinas, SP, Brazil
Supmeca-Paris, Mechanical and Manufacturing Engineering School, Paris, France
e-mail: bayraktar@supmeca.fr
© The Society for Experimental Mechanics, Inc. 2021
R. P. Singh, V. Chalivendra (eds.), Mechanics of Composite, Hybrid and Multifunctional Materials, Volume 6,
Conference Proceedings of the Society for Experimental Mechanics Series, https://doi.org/10.1007/978-3-030-59868-6_16
107