Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3
One common material for engine applications is the AlSi9Cu3 alloy. This alloy has a good castability, excellent machinability, medium strength, and low specific weight. The study was focused on the investigation of the effect of the solution heat treatment on the microstructure and mechanical proper...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
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irk-123456789-484472013-08-19T19:09:52Z Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 Panuskova, M. Tillova, E. Chalupova, M. Научно-технический раздел One common material for engine applications is the AlSi9Cu3 alloy. This alloy has a good castability, excellent machinability, medium strength, and low specific weight. The study was focused on the investigation of the effect of the solution heat treatment on the microstructure and mechanical properties of the alloy (strength - Rm, hardness - HBS). The temperatures of the solution heat treatment were 505°C, 515°C, and 525°C± 5°C and the solution time rangedfrom 0 to 32 h (0, 2, 4, 8, 16, and 32 h). Alloy AlSi9Cu3 contained α-matrix, eutectic silicon, and other Fe- and Cu-rich phases with different morphology (needle-like, Chinese script, skeleton-like, blocky, etc.). The results obtained revealed the relation between the mechanical properties and the morphologies ofthe eutectic silicon and thepredominant copper-rich phase Al-Al2Cu-Si during the solution treatment. Сплав AlSi9Cu3 является одним из материалов, широко используемых в двигателестроении. Он имеет хорошую жидко-текучесть, отличную обрабатываемость, среднюю прочность и низкий удельный вес. Основное внимание в данном исследовании было направлено на исследование влияния гомогенизации на микроструктуру и механические свойства этого сплава (прочность исходного материала Кт, твердость НВХ). Обработка проводилась при температурах 505, 515 и 525°С± 5°С, длительность обработки колебалась в пределах 0...32 ч (0, 2, 4, 8, 16 и 32 ч). Сплав AlSi9Cu3 содержал α-матрицу, эвтектический кремний и другие фазы, богатые железом и медью, имеющие различную структуру (игольчатую, иероглифоподобную, ажурную, глыбообразную и т.п.). Полученные результаты показали существование зависимости между механическими свойствами и морфологиями эвтектического кремния и богатой медью Al-Al2Cu-Si-фазы, преобладающей во время гомогенизации. 2008 Article Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 / M. Panuskova, E. Tillova, M. Chalupova // Проблемы прочности. — 2008. — № 1. — С. 109-112. — Бібліогр.: 6 назв. — англ. 0556-171X http://dspace.nbuv.gov.ua/handle/123456789/48447 539.4 en Проблемы прочности Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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Научно-технический раздел Научно-технический раздел Panuskova, M. Tillova, E. Chalupova, M. Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 Проблемы прочности |
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One common material for engine applications is the AlSi9Cu3 alloy. This alloy has a good castability, excellent machinability, medium strength, and low specific weight. The study was focused on the investigation of the effect of the solution heat treatment on the microstructure and mechanical properties of the alloy (strength - Rm, hardness - HBS). The temperatures of the solution heat treatment were 505°C, 515°C, and 525°C± 5°C and the solution time rangedfrom 0 to 32 h (0, 2, 4, 8, 16, and 32 h). Alloy AlSi9Cu3 contained α-matrix, eutectic silicon, and other Fe- and Cu-rich phases with different morphology (needle-like, Chinese script, skeleton-like, blocky, etc.). The results obtained revealed the relation between the mechanical properties and the morphologies ofthe eutectic silicon and thepredominant copper-rich phase Al-Al2Cu-Si during the solution treatment. |
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Article |
| author |
Panuskova, M. Tillova, E. Chalupova, M. |
| author_facet |
Panuskova, M. Tillova, E. Chalupova, M. |
| author_sort |
Panuskova, M. |
| title |
Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 |
| title_short |
Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 |
| title_full |
Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 |
| title_fullStr |
Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 |
| title_full_unstemmed |
Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 |
| title_sort |
relation between mechanical properties and microstructure of cast aluminum alloy alsi9cu3 |
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Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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2008 |
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Научно-технический раздел |
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http://dspace.nbuv.gov.ua/handle/123456789/48447 |
| citation_txt |
Relation between Mechanical Properties and Microstructure of Cast Aluminum Alloy AlSi9Cu3 / M. Panuskova, E. Tillova, M. Chalupova // Проблемы прочности. — 2008. — № 1. — С. 109-112. — Бібліогр.: 6 назв. — англ. |
| series |
Проблемы прочности |
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AT panuskovam relationbetweenmechanicalpropertiesandmicrostructureofcastaluminumalloyalsi9cu3 AT tillovae relationbetweenmechanicalpropertiesandmicrostructureofcastaluminumalloyalsi9cu3 AT chalupovam relationbetweenmechanicalpropertiesandmicrostructureofcastaluminumalloyalsi9cu3 |
| first_indexed |
2025-07-04T08:57:33Z |
| last_indexed |
2025-07-04T08:57:33Z |
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1836706120271396864 |
| fulltext |
UDC 539. 4
R e la t io n b e t w e e n M e c h a n ic a l P r o p e r t i e s a n d M ic r o s t r u c t u r e o f C a s t
A lu m in u m A llo y A lS i9 C u 3
M . P an u sk o v a ,1a E . T illo v a ,1b and M . C h a lu p ova1,c
1 University o f Zilina, Faculty of Mechanical Engineering, Department o f Materials Engineering,
Zilina, Slovak Republic
a marta.panuskova@fstroj.uniza.sk, b eva.tillova@fstroj.uniza.sk,
c maria.chalupova@fstroj.uniza.sk
One common material fo r engine applications is the AlSi9Cu3 alloy. This alloy has a good
castability, excellent machinability, medium strength, and low specific weight. The study was
focused on the investigation o f the effect o f the solution heat treatment on the microstructure and
mechanical properties o f the alloy (strength - Rm, hardness - HBS). The temperatures o f the
solution heat treatment were 505°C, 515°C, and 525°C± 5°C and the solution time ranged from 0 to
32 h (0, 2, 4, 8, 16, and 32 h). Alloy AlSi9Cu3 contained a-matrix, eutectic silicon, and other Fe-
and Cu-rich phases with different morphology (needle-like, Chinese script, skeleton-like, blocky,
etc.). The results obtained revealed the relation between the mechanical properties and the
morphologies o f the eutectic silicon and the predominant copper-rich phase Al-A l2Cu-Si during the
solution treatment.
K eyw o rd s : aluminum cast alloys, microstructure, m echanical properties, intermetallic
phases, fracture zones.
In troduction . In industry, particularly in aerospace and autom obile branches, there
is a tendency to reduce costs, prices, and w eight o f com plete products. In this respect, o f
importance are easy availability and the industry requirements for environmental
protection, i.e ., recyclability o f industry materials. Significant is the fact that the density o f
steel materials is three tim es higher than that o f aluminum alloys. The substitution o f
aluminum alloys for m agnesium ones is a m om entous aim in the developm ent o f m any
branches o f industry, but m agnesium alloys have a lo t o f disadvantages: the contact w ith
m agnesium m elts is hazardous that excludes their recycling possib ilities [ 1].
Cost effectiveness o f the production and application o f aluminum alloys is being
constantly im proved, e.g., at present an average European autom obile contains about 90%
o f recycled aluminum alloys out o f the total share o f alum inum alloys in an autom obile
[1]. A l-S i cast alloys are extensively used in the autom otive and aerospace industries due
to their excellent castability, good m echanical properties and wear resistance. The addition
o f alloying elem ents such as M g and Cu m ake these a lloys heat treatable further
im proving their m echanical properties and allow ing their use in new, more dem anding
applications (e.g ., engines, cylinder heads, etc.). The m ost used heat treatment for these
A l-S i-C u cast alloys is the solution treatment fo llow ed by age hardening that is required
for the precipitation o f the A l2Cu hardening constituent. The solution heat treatment o f
A l-S i-C u cast alloys affects the microstructure o f the alloy in three aspects, namely: the
dissolution o f coarse A l2Cu, hom ogenization o f the microstructure, im provem ent o f
eutectic silicon m orphology (fragmentation, spheroidization, and coarsening), and the
ensuing changes in the fracture zones [2 ].
The present study is a part o f a larger research project, w hich w as conducted to
investigate and to provide a better understanding o f the influence o f heat treatment on the
structure (structural analyses) and m echanical properties o f cast A l-S i-C u alloys. The
study w as conducted on the m ost popular A lSi9C u3 alloy that contains about 9% Si and
3% Cu.
© M. PANUSKOVA, E. TILLOVA, M. CHALUPOVA, 2008
ISSN 0556-171X. Проблемы прочности, 2008, N 1 109
mailto:marta.panuskova@fstroj.uniza.sk
mailto:eva.tillova@fstroj.uniza.sk
mailto:maria.chalupova@fstroj.uniza.sk
M. Panuskovâ, E. Tillovâ, and M. Chalupovâ
T a b l e 1
Chemical Composition o f AlSi9Cu3 Alloy
Element Si Cu Mn Zn Mg Ni Pb Fe Ti Al
wt.% 10.7 2.4 0.22 1.1 0.27 0.08 0.11 0.9 0.03 base
E xperim ental. Experiments were performed on AlSi9C u3 cast alloy w hose chemical
com position is g iven in Table 1. This a lloy has a low er corrosion resistance and is suitable
for high-temperature (up to m ax. 25 0 oC) applications (dynam ically exposed casts). In this
case, the requirements to its m echanical properties are not so restrictive. This cast alloy
w as produced at the Foundry Co. CONFAL, a.s., S lovenska Lupca.
A lloys o f the A l-S i-C u type are usually heat treated in order to develop higher
m echanical properties. Heat treatment involves solution and aging heat treatments during
w hich a series o f changes in microstructure occur w hich then lead to the im provem ent o f
strength. These changes in microstructure include the d issolution o f precipitates,
hom ogenization o f the cast structure, such as m inim ization o f alloying elem ent
segregation, spheroidization and coarsening o f eutectic silicon, and precipitation o f finer
hardening phases [3, 4]. D ifferent solution heat treatment procedures were used to
evaluate their influence on the m echanical properties (tensile strength, R m, and hardness,
HBS) and on the m orphology o f the eutectic Si and Cu-rich phase (ternary eutectic
A l-A l2C u -S i phase) and on ensuing changes in the fracture pattern.
The experim ents were carried out in an electric induction furnace. The castings were
subjected to the solution treatment at three temperatures (505, 515, and 525°C) during the
periods o f tim e ranging from 2 to 32 hours (0, 2, 4, 8 , 16, and 32 h), then quenched in
warm water in the temperature range from 40 to 60oC, and aged naturally at room
temperature for 24 hours. The sam ples for m icroscopic analysis were prepared by
standard m etallographic procedures (w et ground, D P polished w ith diam ond pastes and
etched b y D ix-K eller, H N O 3 or M A [2]).
a b c
Fig. 1. Typical microstructure patterns in AlSi9Cu3 cast alloy (etched by a Dix Keller solution):
(a) a-matrix, platelets o f eutectic Si; (b) Al5FeSi, A l-A l2Cu-Si phase; (c) A l15(MnFe)3Si phase -
“Chinese script.”
Generally, the as-cast microstructure o f A lSi9C u3 alloy com prises a-m atrix, the
platelets o f eutectic silicon (dark grey) (Fig. 1a) and m any intermetallic phases. In this
alloy there w ere also observed the fo llow ing intermetallic phases: the iron phase A l5FeSi
in the shape o f black needles (Fig. 1b), w hich has a m onoclin ic crystal structure and
precipitates in interdendritic and intergranular regions as platelets [5]. Long A l5FeSi
platelets (more than 500 [im ) can adversely affect the m echanical properties, especially
ductility, and they also lead to the formation o f excessive shrinkage porosity defects in
castings. The A l5F eSi phase appears as a nucleation locality for Cu-rich phase A l-
A l2C u -S i (Fig. 1b).
Another com m on iron intermetallic is the A l15(M nFe)3Si phase w ith a cubic crystal
structure [6 ]. This phase has a com pact m orphology in the form o f “C hinese script”
110 ISSN Ü556-171X. Проблемыг прочности, 2ÜÜ8, N 1
Relation between Mechanical Properties and Microstructure
(Fig. 1c) and thus it contains less initiated cracks as com pared to the needle-like phase
A l5FeSi. The effect o f the applied heat treatment on these iron-rich phases (A l5F eSi - 16%
Fe, A l15(M nFe)3Si - 14% Fe) is not significant and results on ly in partial segm entation o f
these phases. H alf or more o f copper is found as a com ponent o f intermetallic com pounds,
primarily, the A l2Cu phase w ith tetragonal crystal structure precipitates in tw o distinct
m orphologies: A l2Cu and in the form o f b locky phase w ith a h igh copper concentration
~38-40% Cu (ternary eutectic A l-A l2C u -S i - Fig. 2a). These com pounds that form at the
later stages o f freezing are located in the interdendritic regions and at the grain
boundaries. Gradual d issolving o f the Cu-rich phase occurs w ith increasing heat treatment
temperature (Fig. 2) and this fact is also confirm ed by harness m easurem ent results.
a b c
Fig. 2. The influence o f heat treatment on the morphology o f the A l-A l2Cu-Si phase: (a) untreated;
(b) at 515°C/4 hours; (c) at 525°C/4 hours.
The im provem ent o f the eutectic silicon m orphology and its distribution have the
m ost significant influence on the changes in the m echanical properties (Fig. 3). The
m orphology o f the eutectic silicon not subjected to heat treatment has the shape o f
platelets (Fig. 3a). Figure 3 b -d demonstrates changes in the eutectic Si m orphology
caused by the solution treatment w ith a holding tim e o f 8 hours. A t temperatures o f 505
and 515°C gradual spheroidization o f the eutectic Si particles begins (Fig. 3b and c). A s
the solution treatment continued to the temperature 525°C, the spheroidized particles
gradually grew larger (overcoarsed) (Fig. 3d).
a b c d
Fig. 3. Changes in the eutectic silicon morphology during heat treatment: (a) untreated; (b) heat
treated at 505°C during 8 hours; (c) heat treated at 515°C during 8 hours; (d) heat treated at 525°C
during 8 hours.
These changes in the eutectic Si influence the the characterpattern o f the fracture
zones as w ell. In the eutectic silicon not subjected to the solution treatment, brittle fracture
fragile breach o f the eutectic platelets and ductile failure o f the a-m atrix are observed.
With gradual spheroidization o f the eutectic Si, the share o f the ductile failure in the alloy
increases.
The microstructure o f A lSi9C u3 alloy is a reflection o f the m echanical properties
(Fig. 4). The increase in the strength and hardness values is significant ch iefly for
temperatures o f 505 and 515°C and for holding tim e o f 8 hours at the m ost. B y the eighth
hour o f the holding tim e the values o f the m echanical properties (ch iefly HBS) begin to
decrease. This trend is typical for all solution heat treatment temperatures and relates to
ISSN 0556-171X. npoôëeubi npounocmu, 2008, N 1 111
M. Panuskova, E. Tillova, and M. Chalupova
gradual coarsening o f the eutetectic Si for the hold tim e longer than 8 hours (Fig. 4). At
the a temperature o f 525°C a decrease in the values o f the m echanical properties is
observed due to a significant coarsening o f the eutectic Si (Fig. 3d).
-
B— - — *
- t — 505°C
—■=515 DC
—* —525 DC
------1
0 4 8 12 16 20 24 2 8 32 36
Time of heat solution treatment [h]
Fig. 4. Changes in the mechanical properties o f AlSi9Cu3 alloy during heat treatment.
With a deincrease in the heat treatment temperatures, gradual dissolution o f the
Cu-rich phase takes place and this fact also confirm s the results obtained for hardness and
tensile strength. With an increase in the solution treatment temperature, the hardness and
strength values increase to a m axim um value at 515°C and then decrease. Hardness
correlates w ithis a reflection o f the solution strengthening and silicon particle distribution
in the matrix. Temperature 515°C is a suitable appropriate temperature for this alloy.
B elow this temperature, the solutionization process is insufficient, w hereas above it,
overcoarsening o f the Si particles and m elting o f A l2Cu m elting A l2Cu occurs. These two
unsatisfied conditionsaspects all result in the reduction o f hardness and strength.
C onclusions. The contribution investigation w as focused on the influence o f the
solution heat solution treatment on the microstructure and m echanical properties (R m and
HBS) o f aluminum cast a lloy A lSi9C u3 for autom otive applications. A s show n by a the
results shown, the optim aoptim um l conditions o f the heat solution heat treatment for this
alloy is are the temperature 515°C and holding tim e m ax. 8 hours. The changes o f in the
microstructure confirm ed that these outcom es. A heat treatment by temperature o f heat
treatment 525°C get leads to gradual coarsening o f the eutectic Si, decreasing ofing o f the
values o f the m echanical properties, values and d issolving d issolution o f the ternary
eutectic A l-A l2C u-Si.
Acknowledgments. The authors acknowledge the VEGA No. 1/2090/05 and No. 1/3153/06
for the financial support o f this work.
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AlSi7Mg-Legierungen,” in: Fortschritt-Berichte VDI, Reihe 5, No. 457, VDI Verlag,
Düsseldorf (1996).
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Opolskiej, Poland (2005), pp. 89-94.
4. E. Tillova, M. Panuskova, and M. Chalupova, “Influence o f the solution treatment on the
structure and properties o f cast AlSi9Cu3 alloys,” in: Fraktography’06, Starö Lesn6 (2006),
pp. 493-496.
5. E. Tillova, M. Panuskova, and M. Chalupova, “Metallograpische Analyse von A l-S i-C u
Gusslegierungen,” Berichte und Informationen, 2/2006, 14, Dresden, SRN (2006), pp. 49-55.
6. C. T. Rios and R. Caram, “Intermetallic compounds in the A l-S i-C u system,” Acta
Mikroskopica, 12, No. 1, 77-81 (2003).
Received 28. 06. 2007
112 ISSN 0556-171X. n poöxeu u npouHocmu, 2008, № 1
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