In this study, the microstructural evolution of Al-Fe-V-Si alloy prepared by mechanical alloying
starting from elemental powders was studied. X-ray diffraction results showed that by increasing the
milling time, peak shifting and peak broadening of Al reflections occur due to dissolution of alloying
elements and grain refinement, respectively. Reduction of Al lattice parameter by increasing the milling
time indicates that an Al based solid solutions formed during mechanical alloying and solute concentration
increased by increasing the milling time. After 60 h of milling, the microstructure consisted of a
nanocrystalline Al solid solutions with a grain size of 19 nm and an internal strain of 0.55 in which Si
phase was dispersed. In contrast to previous studies on rapidly solidified Al-Fe-V-Si alloys, there is no
formation of trace of Al12(Fe,V)3Si or other intermetallic compounds in the as-milled condition.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3509

Ashrafi, H.

Emadi, R.

Enayati, M.H.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 3, 03CNN12(3pp) (2012)   2304-1862/2012/1(3)03CNN12(3) 03CNN12-1  2012 Sumy State University Formation of Nanocrystalline Solid Solution in Al-Fe-V-Si Alloys by Mechanical Alloying  H. Ashrafi*, M.H. Enayati†, R. Emadi‡   Isfahan University of Technology, Isfahan 84156-83111, Iran  (Received 18 June 2012; published online 22 August 2012)  In this study, the microstructural evolution of Al-Fe-V-Si alloy prepared by mechanical alloying starting from elemental powders was studied. X-ray diffraction results showed that by increasing the milling time, peak shifting and peak broadening of Al reflections occur due to dissolution of alloying elements and grain refinement, respectively. Reduction of Al lattice parameter by increasing the milling time indicates that an Al based solid solutions formed during mechanical alloying and solute concentration increased by increasing the milling time. After 60 h of milling, the microstructure consisted of a nanocrystalline Al solid solutions with a grain size of 19 nm and an internal strain of 0.55 in which Si phase was dispersed. In contrast to previous studies on rapidly solidified Al-Fe-V-Si alloys, there is no formation of trace of Al12(Fe,V)3Si or other intermetallic compounds in the as-milled condition.  Keywords: solid solutions; Al-Fe-V-Si alloy; nanocrystalline; mechanical alloying.    PACS numbers: 81.20.Ev, 81.05.Bх                                                             * h.ashrafi@ma.iut.ac.ir † ena78@cc.iut.ac.ir ‡ remadi@cc.iut.ac.ir  1. INTRODUCTION  Al-Fe-V-Si alloys are of interesting high tempera-ture Al alloys due to their good combination of ductility, room and high temperature strengths and fracture toughness attributed to uniformly distributed Al12(Fe,V)3Si intermetallic phase, which are resistant to coarsening [1]. The low coarsening rate of Al12(Fe,V)3Si phase at elevated temperatures is a result of low solid solubility and low diffusivity of the alloying elements in Al, that are basic requirements for prevent Ostwald ripening [2,3]. Because of low coarsening rate and high volume fraction of Al12(Fe,V)3Si intermetallic phase that inhibit recrystallization and limiting grain growth, the mechanical properties of Al-Fe-V-Si alloys do not changes significantly even after 100 hours an-nealing at temperatures as high as 500 C [1]. Al-Fe-V-Si alloys are produced by rapid solidifica-tion techniques such as melt spinning [4], gas atomiza-tion [5] and spray co-deposition [6]. The microstructure of rapidly solidified alloys often consisted of fine precip-itates of  Al12(Fe,V)3Si phase in ultrafine grained Al matrix [4]. Recently, mechanical alloying (MA) become of widespread interest method for the producing of al-uminium alloys [3,7,8]. MA is a non-equilibrium solid state processing which used to produce a variety of ma-terials and alloys: super saturated solid solutions, amorphous materials, intermetallic compounds and metal-matrix composites [9]. It was found that MA led to formation of nanostructured solid solution in many Al-Fe base systems with high Al contents [3,7].  The aim of this study is to investigate the effect of MA on microstructure of Al-Fe-V-Si alloys starting from elemental powders. Then, a comparison has been performed between the as-milled products and those for rapidly solidified Al-Fe-V-Si alloys that found in the literatures.  2. EXPERIMENTAL  Mixtures of pure Al (99.5%, 10 – 40 m, Khorasan powder metallurgy), Fe (99.8%, 100 m, merck), V (99.5%, 500 m, fluka) and Si (99.8%, 20 – 80 m, merck) with a nominal composition of Al-11.7Fe-1.3V-2.3Si (wt.%) were used as starting materials. MA was performed in a high energy planetary ball mill (Fritsch P7 type) at room temperature and argon atmosphere with a rotation speed of 500 rpm and a ball- powder mass ratio of 10:1 for 60 h. In order to preventation of severe sticking of Al powders to balls and vial, 1.5 wt.% stearic acid was used as process controlling agent (PCA). Structural changes of powders during ball mill-ing was determined by X-ray diffraction (XRD) in a Philips X' PERT MPD diffractometer using filtered Cu K  radiation (   0.15406 nm). The morphology and microstructure of as-milled powder was characterized by scanning electron microscopy (SEM) using a Philips XL30 at an accelerating voltage of 30 kV. The Grain size and internal strain of milled powders were evalu-ated from the XRD line broadening using the William-son-Hall equation [10]:   0.92Cos SinD  (2.1)  Where  is peak breadth at half maximum intensity,  is the Bragg angle,  is the wavelength of the X-ray (0.15406 nm), D is the average grain size and  is the mean value of internal strain.  3. RESULTS AND DISCUSSION  The XRD patterns of alloy powder mixture at differ-ent milling times are shown in Fig. 1. As seen, in the initial mixture of alloy powders, only the diffraction peaks of Al and Si can be seen. The absence of Fe and V diffraction peaks are due to overlapping and low concentrations, respectively. By increasing the  H. ASHRAFI, M.H. ENAYATI, R. EMADI PROC. NAP 1, 03CNN12(2012)   03CNN12-2 milling time, two distinct features are noted in this fig-ure, one is peak broadening of Al reflections and the oth-er is peak displacement of Al to higher angles. The peak broadening is due to the grain refinement and introduc-tion of internal strains, whereas peak displacement sug-gests formation of an Al based solid solutions. It must be noted that after 60 h milling, three small peaks of Si still existed on the XRD pattern, indicating that an amount of this element has been dispersed in Al matrix as small isolated particles.    Fig. 1 – The XRD patterns of Al-11.7Fe-1.3V-2.3Si powder mixture after different milling times  Formation of an Al based solid solutions can bet-ter be understood from the changes in Al lattice pa-rameter. Variations of Al lattice parameter as a function of milling time is presented in Fig. 2. It is noted that the lattice parameter decreases by in-creasing the milling time. The observed decrease in the lattice parameter indicates dissolution of smaller Fe, V and Si atoms (Table 1) into fcc Al and for-mation of an Al-based solid solutions. By increasing the milling time, solute concentration increased.    Fig. 2 – Variations of Al lattice parameter as a function of milling time  Table 1 – Atomic radius of alloying elements  element Al Fe V Si Atomic radius (nm) 0.143 0.126 0.111 0.134  Table 2 presents the lattice parameter, grain size and internal strain of Al in the as-mixed state and after 60 h MA. As observed, the estimated grain size and internal strain of Al after 60 h of MA were 19 nm and 0.55, re-spectively.  Table 2 – Lattice parameter, grain size and internal strain of Al at different conditions  condition lattice parameter (A) Grain size (nm) Internal strain (%) as-mixed 4.06 350 - 60 h MA 4.044 19 0.55  Cross-sectional SEM image of 60 h mechanically al-loyed powders are presented in Fig. 3. A nearly uniform microstructure is seen in the SEM image, but some bright particles with a size smaller than 1µm also ob-served in the matrix, indicates that all the alloying ele-ments have not been dissolved in Al matrix. The uniform microstructure in this stage shows that alloying take place well and nearly a homogeneous microstructure has been obtained after MA.    Fig. 3 – Cross-sectional SEM image of 60 h mechanically alloyed powder mixture  Fig. 4 illustrates the morphology of alloy powder particles after 60 h of ball milling. As seen, after 60 h milling the particles became very fine due to the ball-powder-ball collisions and fracturing of brittle powder particles during MA. The milled powder particles exhibit equiaxed morphology with an average particle size of 12 m.    Fig. 4 – Morphology of alloy powder mixture after 60 h milling  Table 3 compares the phases presented after MA of Al-Fe-V-Si alloys with those obtained by rapid solidification techniques. As seen, rapid solidification techniques lead to formation of intermetallic phases in Al matrix, while in the present work no trace of any intermetallic compound  FORMATION OF NANOCRYSTALLINE SOLID SOLUTION … PROC. NAP 1, 03CNN12 (2012)   03CNN12-3 was detected after MA. The microstructure of as-milled product consisted of nanocrystalline Al solid solution in which Si phase was dispersed.  Table 3 – Comparison between presented phases after MA and various rapid solidification techniques of Al-Fe-V-Si alloys  process phases after process reference MA Al+Si This work Melt spinning Al+Al12(Fe,V)3Si [4] Spray co-deposition Al+Al12(Fe,V)3Si+Al13Fe4 [6] Gas atomization Al+Al12(Fe,V)3Si [5]  4. CONCLUSIONS  The present study of Al-11.7Fe-1.3V-2.3Si alloy shows that nanocrystalline Al-based solid solutions can be formed by MA of elemental powders. XRD results showed that during mechanical alloying, peak broaden-ing of Al reflections occurs as a result of grain refine-ment and enhancement of internal strains. Reduction of Al lattice parameter indicates dissolution of smaller Fe, V and Si atoms into the Al lattice and formation of a nanocrystalline Al solid solution. In contrast to previous studies on rapidly solidified Al-Fe-V-Si alloys, there is no formation of Al12(Fe,V)3Si or other intermetallic com-pounds in the as-milled condition.  REFERENCES  1. R.E. Franck, J.A. Hawk, Scripta Metall. 23, 113 (1989). 2.  S.C. Khatri, A. Lawley, M.J. Koczak, Mater. Sci. Eng. A 167, 11 (1993). 3. M. Zawrah, L. Shaw, Mater. Sci. Eng. A 355, 37 (2003). 4. J.Q. Wang, M.K. Tseng, X.F. Chen, B.J. Zhang, Z. Xianyu, Mater. Sci. Eng. A 179, 412 (1994). 5. S. Hariprasad, S.M.L. Sastry, K.L. Jerina, J. Mater. Sci. 31, 921 (1996). 6. Y. Tang, D. Tan, W. Li, Z. Pan, L. Li, W. Hua, J. Alloys Compd. 439, 103 (2007). 7. T.T. Sasaki, T. Mukaib, K. Hono, Scripta Mater. 57, 189 (2007). 8. S. Mula, S. Ghosh, S.K. Pabi, Mater. Sci. Eng. A 472, 208 (2008). 9. C. Suryanarayana, Prog. Mater. Sci. 46, 1 (2001). 10. G.K. Williamson, W.H. Hall, Acta Metall. 1, 22 (1953). 

Formation of Nanocrystalline Solid Solution in Al-Fe-V-Si Alloys by Mechanical Alloying

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 3, 03CNN12(3pp) (2012) 
 
 
2304-1862/2012/1(3)03CNN12(3) 03CNN12-1  2012 Sumy State University 
Formation of Nanocrystalline Solid Solution in Al-Fe-V-Si Alloys by Mechanical Alloying 
 
H. Ashrafi*, M.H. Enayati†, R. Emadi‡ 
 
 Isfahan University of Technology, Isfahan 84156-83111, Iran 
 
(Received 18 June 2012; published online 22 August 2012) 
 
In this study, the microstructural evolution of Al-Fe-V-Si alloy prepared by mechanical alloying 
starting from elemental powders was studied. X-ray diffraction results showed that by increasing the 
milling time, peak shifting and peak broadening of Al reflections occur due to dissolution of alloying 
elements and grain refinement, respectively. Reduction of Al lattice parameter by increasing the milling 
time indicates that an Al based solid solutions formed during mechanical alloying and solute concentration 
increased by increasing the milling time. After 60 h of milling, the microstructure consisted of a 
nanocrystalline Al solid solutions with a grain size of 19 nm and an internal strain of 0.55 in which Si 
phase was dispersed. In contrast to previous studies on rapidly solidified Al-Fe-V-Si alloys, there is no 
formation of trace of Al12(Fe,V)3Si or other intermetallic compounds in the as-milled condition. 
 
Keywords: solid solutions; Al-Fe-V-Si alloy; nanocrystalline; mechanical alloying. 
 
  PACS numbers: 81.20.Ev, 81.05.Bх 
 
 
                                                          
* h.ashrafi@ma.iut.ac.ir 
† ena78@cc.iut.ac.ir 
‡ remadi@cc.iut.ac.ir  
1. INTRODUCTION 
 
Al-Fe-V-Si alloys are of interesting high tempera-
ture Al alloys due to their good combination of ductility, 
room and high temperature strengths and fracture 
toughness attributed to uniformly distributed 
Al12(Fe,V)3Si intermetallic phase, which are resistant 
to coarsening [1]. The low coarsening rate of 
Al12(Fe,V)3Si phase at elevated temperatures is a result 
of low solid solubility and low diffusivity of the alloying 
elements in Al, that are basic requirements for prevent 
Ostwald ripening [2,3]. Because of low coarsening rate 
and high volume fraction of Al12(Fe,V)3Si intermetallic 
phase that inhibit recrystallization and limiting grain 
growth, the mechanical properties of Al-Fe-V-Si alloys 
do not changes significantly even after 100 hours an-
nealing at temperatures as high as 500 C [1]. 
Al-Fe-V-Si alloys are produced by rapid solidifica-
tion techniques such as melt spinning [4], gas atomiza-
tion [5] and spray co-deposition [6]. The microstructure 
of rapidly solidified alloys often consisted of fine precip-
itates of  Al12(Fe,V)3Si phase in ultrafine grained Al 
matrix [4]. Recently, mechanical alloying (MA) become 
of widespread interest method for the producing of al-
uminium alloys [3,7,8]. MA is a non-equilibrium solid 
state processing which used to produce a variety of ma-
terials and alloys: super saturated solid solutions, 
amorphous materials, intermetallic compounds and 
metal-matrix composites [9]. It was found that MA led 
to formation of nanostructured solid solution in many 
Al-Fe base systems with high Al contents [3,7].  
The aim of this study is to investigate the effect of 
MA on microstructure of Al-Fe-V-Si alloys starting 
from elemental powders. Then, a comparison has been 
performed between the as-milled products and those for 
rapidly solidified Al-Fe-V-Si alloys that found in the 
literatures. 
 
2. EXPERIMENTAL 
 
Mixtures of pure Al (99.5%, 10 – 40 m, Khorasan 
powder metallurgy), Fe (99.8%, 100 m, merck), V 
(99.5%, 500 m, fluka) and Si (99.8%, 20 – 80 m, 
merck) with a nominal composition of Al-11.7Fe-1.3V-
2.3Si (wt.%) were used as starting materials. MA was 
performed in a high energy planetary ball mill (Fritsch 
P7 type) at room temperature and argon atmosphere 
with a rotation speed of 500 rpm and a ball- powder 
mass ratio of 10:1 for 60 h. In order to preventation of 
severe sticking of Al powders to balls and vial, 1.5 wt.% 
stearic acid was used as process controlling agent 
(PCA). Structural changes of powders during ball mill-
ing was determined by X-ray diffraction (XRD) in a 
Philips X' PERT MPD diffractometer using filtered Cu 
K  radiation (   0.15406 nm). The morphology and 
microstructure of as-milled powder was characterized 
by scanning electron microscopy (SEM) using a Philips 
XL30 at an accelerating voltage of 30 kV. The Grain 
size and internal strain of milled powders were evalu-
ated from the XRD line broadening using the William-
son-Hall equation [10]: 
 
 
0.9
2Cos Sin
D
  (2.1) 
 
Where  is peak breadth at half maximum intensity,  
is the Bragg angle,  is the wavelength of the X-ray 
(0.15406 nm), D is the average grain size and  is the 
mean value of internal strain. 
 
3. RESULTS AND DISCUSSION 
 
The XRD patterns of alloy powder mixture at differ-
ent milling times are shown in Fig. 1. As seen, in the 
initial mixture of alloy powders, only the diffraction 
peaks of Al and Si can be seen. The absence of Fe 
and V diffraction peaks are due to overlapping and 
low concentrations, respectively. By increasing the 
 H. ASHRAFI, M.H. ENAYATI, R. EMADI PROC. NAP 1, 03CNN12(2012) 
 
 
03CNN12-2 
milling time, two distinct features are noted in this fig-
ure, one is peak broadening of Al reflections and the oth-
er is peak displacement of Al to higher angles. The peak 
broadening is due to the grain refinement and introduc-
tion of internal strains, whereas peak displacement sug-
gests formation of an Al based solid solutions. It must be 
noted that after 60 h milling, three small peaks of Si still 
existed on the XRD pattern, indicating that an amount 
of this element has been dispersed in Al matrix as small 
isolated particles. 
 
 
 
Fig. 1 – The XRD patterns of Al-11.7Fe-1.3V-2.3Si powder 
mixture after different milling times 
 
Formation of an Al based solid solutions can bet-
ter be understood from the changes in Al lattice pa-
rameter. Variations of Al lattice parameter as a 
function of milling time is presented in Fig. 2. It is 
noted that the lattice parameter decreases by in-
creasing the milling time. The observed decrease in 
the lattice parameter indicates dissolution of smaller 
Fe, V and Si atoms (Table 1) into fcc Al and for-
mation of an Al-based solid solutions. By increasing 
the milling time, solute concentration increased. 
 
 
 
Fig. 2 – Variations of Al lattice parameter as a function of 
milling time 
 
Table 1 – Atomic radius of alloying elements 
 
element Al Fe V Si 
Atomic radius 
(nm) 
0.143 0.126 0.111 0.134 
 
Table 2 presents the lattice parameter, grain size and 
internal strain of Al in the as-mixed state and after 60 h 
MA. As observed, the estimated grain size and internal 
strain of Al after 60 h of MA were 19 nm and 0.55, re-
spectively. 
 
Table 2 – Lattice parameter, grain size and internal strain of 
Al at different conditions 
 
condition lattice 
parameter 
(A) 
Grain 
size 
(nm) 
Internal 
strain (%) 
as-mixed 4.06 350 - 
60 h MA 4.044 19 0.55 
 
Cross-sectional SEM image of 60 h mechanically al-
loyed powders are presented in Fig. 3. A nearly uniform 
microstructure is seen in the SEM image, but some 
bright particles with a size smaller than 1µm also ob-
served in the matrix, indicates that all the alloying ele-
ments have not been dissolved in Al matrix. The uniform 
microstructure in this stage shows that alloying take 
place well and nearly a homogeneous microstructure has 
been obtained after MA. 
 
 
 
Fig. 3 – Cross-sectional SEM image of 60 h mechanically 
alloyed powder mixture 
 
Fig. 4 illustrates the morphology of alloy powder 
particles after 60 h of ball milling. As seen, after 
60 h milling the particles became very fine due to the 
ball-powder-ball collisions and fracturing of brittle 
powder particles during MA. The milled powder 
particles exhibit equiaxed morphology with an 
average particle size of 12 m. 
 
 
 
Fig. 4 – Morphology of alloy powder mixture after 60 h milling 
 
Table 3 compares the phases presented after MA of Al-
Fe-V-Si alloys with those obtained by rapid solidification 
techniques. As seen, rapid solidification techniques lead to 
formation of intermetallic phases in Al matrix, while in 
the present work no trace of any intermetallic compound 
 FORMATION OF NANOCRYSTALLINE SOLID SOLUTION … PROC. NAP 1, 03CNN12 (2012) 
 
 
03CNN12-3 
was detected after MA. The microstructure of as-milled 
product consisted of nanocrystalline Al solid solution in 
which Si phase was dispersed. 
 
Table 3 – Comparison between presented phases after MA 
and various rapid solidification techniques of Al-Fe-V-Si alloys 
 
process phases after process reference 
MA Al+Si 
This 
work 
Melt spinning Al+Al12(Fe,V)3Si [4] 
Spray co-
deposition 
Al+Al12(Fe,V)3Si+Al13Fe4 [6] 
Gas atomization Al+Al12(Fe,V)3Si [5] 
 
4. CONCLUSIONS 
 
The present study of Al-11.7Fe-1.3V-2.3Si alloy 
shows that nanocrystalline Al-based solid solutions can 
be formed by MA of elemental powders. XRD results 
showed that during mechanical alloying, peak broaden-
ing of Al reflections occurs as a result of grain refine-
ment and enhancement of internal strains. Reduction of 
Al lattice parameter indicates dissolution of smaller Fe, 
V and Si atoms into the Al lattice and formation of a 
nanocrystalline Al solid solution. In contrast to previous 
studies on rapidly solidified Al-Fe-V-Si alloys, there is no 
formation of Al12(Fe,V)3Si or other intermetallic com-
pounds in the as-milled condition. 
 
REFERENCES 
 
1. R.E. Franck, J.A. Hawk, Scripta Metall. 23, 113 (1989). 
2.  S.C. Khatri, A. Lawley, M.J. Koczak, Mater. Sci. Eng. A 
167, 11 (1993). 
3. M. Zawrah, L. Shaw, Mater. Sci. Eng. A 355, 37 (2003). 
4. J.Q. Wang, M.K. Tseng, X.F. Chen, B.J. Zhang, Z. Xianyu, 
Mater. Sci. Eng. A 179, 412 (1994). 
5. S. Hariprasad, S.M.L. Sastry, K.L. Jerina, J. Mater. Sci. 
31, 921 (1996). 
6. Y. Tang, D. Tan, W. Li, Z. Pan, L. Li, W. Hua, J. Alloys 
Compd. 439, 103 (2007). 
7. T.T. Sasaki, T. Mukaib, K. Hono, Scripta Mater. 57, 189 
(2007). 
8. S. Mula, S. Ghosh, S.K. Pabi, Mater. Sci. Eng. A 472, 208 
(2008). 
9. C. Suryanarayana, Prog. Mater. Sci. 46, 1 (2001). 
10. G.K. Williamson, W.H. Hall, Acta Metall. 1, 22 (1953). 


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Formation of Nanocrystalline Solid Solution in Al-Fe-V-Si Alloys by Mechanical Alloying

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