A Novel Trend In Producing Ceramic Based Nanocomposite ... · Mohamed. M. EL-Sayed & Mohamed M....

------------- Journal of Sebha University - (Pure and Applied Sciences) - Vol. 8 No.2 (2009) --------------- 5

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A Novel Trend In Producing Ceramic Based Nanocomposite Material using α-

Al2O3 Powder and FeCl2 Solution as Starting Materials Mohamed. M. EL-Sayed & Mohamed M. Saleh

Sebha University, Sebha

E-mail: [email protected] or [email protected] --------------------------------------------------------------------------------------------------------------------------------

Abstract In recent years, it has been established that the incorporation of nano metallic particles

into a ceramic matrix lead to enhanced fracture properties. Alumina-iron nanocomposite powders

are prepared by a two-step process. In the first step, -alumina-ferrous chloride powder mixture

was formed by mixing -alumina powders with ferrous chloride solution followed by drying in

an oven at 60 oC for 24 h. In the second step, the ferrous chloride in the dry power mixture was

selectively reduced to iron particles. A reduction temperature of 750 oC for 15 min in dry H2 was

chosen based on the thermodynamic calculations The concentration of iron in ferrous chloride

solution was calculated to give 20 vol.% Fe in the final composite product. Two techniques were

used to produce composite bulk materials. The alumina-iron nanocomposite powders were

divided to two batches. The first batch of the produced mixture was hot pressed at 1400 C and

27 MPa for 30 min in a graphite die. To study the effect of oxygen on the Al2O3/Fe interface

bonding and mechanical properties of the composite, the second batch was heat treated in air at

700 C for 20 min to partially oxidize the iron particles before hot pressing Characterization of

the composites was undertaken by conventional density measurements, X-ray diffractometry

(XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and

electron probe microanalysis (EPMA). The mechanical properties of the produced composites are

also investigated. The suggested processing route (mixing, reduction and hot pressing) produces

ceramic-metal nanocomposite much tougher than the virgin alumina. The fracture strength of the

produced Al2O3/Fe nanocomposite is nearly twice that of the pure alumina. The presence of

spinal phase, FeAl2O4, as thick layer around the iron particles in the alumina matrix has a

detrimental effect on interfacial bonding between iron and alumina and the fracture properties of

the composite.

Key Words: Ferrous chloride, reduction, alumina-iron nanocomposite, spinal phase. --------------------------------------------------------------------------------------------------------------------------------

1. Introduction The application of ceramics as

engineering parts is handicapped by their

brittleness. It is well accepted that the

fracture toughness and in some cases

fracture strength of a brittle, ceramic

material can be increased through the

addition of a dispersed second phase. One

approach to this involves the introduction of

a ductile metallic phase into the oxide

ceramic matrix. This metallic phase can be

continuous along the grain boundaries of the

ceramic grains[1-5], or it can be highly

dispersed with a particulate morphology[6-11].

Of course, the processing of this material is

difficult, especially in the latter case, where

one desires a uniform dispersion of fine

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-------------------------------------------------------------------------- Mohamed. M. EL-Sayed & Mohamed M. Saleh.

6 ------------- Journal of Sebha University - (Pure and Applied Sciences) - Vol. 8 No.2 (2009) ---------------

metallic particles within a fine-grained

ceramic matrix[12].

The toughening mechanisms of the

ceramic-metal composites have already been

investigated[6,11,13] and the enhancement is

believed to be produced by the plastic

inclusions which bridge the crack and are

stretched as it opens, absorbing energy

which contributes to the toughness.

Nevertheless, some interface conditions have

to be fulfilled in order for the plastic

deformation to be fully exploited[14-16].

Two main difficulties in the ceramic-

metal composites still remain and restrict

their use for structural application. The first

difficulty is the poor interfacial cohesion

between the metallic particles and the

ceramic matrix and the second is the highly

non-uniform and large metallic particles

dispersion often associated with a high

content of pores[17], where large amounts of

metal phase often interfere with the sintering

mechanisms. It has been proposed to reduce

such unfavourable characteristics by a

reduction of the mean grain size to the

nanometer region[8,18,19]. Both, the

achievable regularity of metallic dispersion

and the interfacial cohesion may be affected

by the grain size. Recently, many research

results showed that the toughness of ceramic

materials can be increased by utilizing nano

powder as starting materials[20-22].

Applications such as high

temperature engine components, catalysts

and alloys resistant to high temperature

oxidation have placed increasing emphasis

on metal-ceramic interfacial phenomena.

Although great studies have been made in

these areas[23,24], more work is needed before

a general understanding of these phenomena

can be reached.

Chemical reaction at ceramic-metal

interfaces can result in the formation of

intermediate phases and this may have a

marked effect on the interfacial properties

and thus on the final properties of the

produced composites. The reaction products

at alumina-metal interfaces are normally

spinel-type compounds. In alumina-metal

composites, the metal is either separated

from the alumina matrix by a double oxide

phase or is directly in contact with the

alumina. Systems Al2O3-MAl2O4-M, where

M stands for metal, are likely to exist when

the MO oxide is easy to form and is then

able to react with alumina to form an

MAl2O4 spinel phase. For example, such

systems were observed with M = Cu[25],

Mg[26], Ni[16]. Factors determining the effect

of interphase formation on bond strength

involve the extent of reaction, thickness of

reaction product, the mechanical properties

of the interphase, the stability of the

interphase, and its compatibility with the

metal and the ceramic.

As it was reported[12] that the mixing

of alumina powder and iron powder is

difficult due to both the tendency of

agglomeration of soft iron powders at higher

content and the difference in densities.

Therefore, the main aims of the present work

were to suggest a new technique to

overcome this problem and to produce

alumina-iron nanocomposite. Alumina-iron

nanocomposite powders are prepared by a

selective reduction process in which powder

mixture of -alumina and ferrous chloride

solution; as a source of iron, is reduced

selectively to produce -alumina-iron

mixture. The concentration of iron in Fecl2

solution was calculated to give 20 vol.% Fe

in the final composite. Microstructure and

-------------------------------------------------------------------------------- A Novel Trend In Producing Ceramic Based

------------- Journal of Sebha University - (Pure and Applied Sciences) - Vol. 8 No.2 (2009) ---------------7

mechanical properties of the produced

composites by hot pressing are examined.

The effect of heat treatment in presence of

oxygen on the formation of the spinel phase

and mechanical properties of the composite

are also investigated.

2. Experimental Procedures

2.1 Fabrication of the composites α-alumina powder (100 nm average

particle size and 99.99 % purity) was mixed

with ferrous chloride solution (as a source

material for iron) in a small hand mixer for

30 min. To achieve homogenous mixture of

α-alumina and ferrous chloride before

reduction and hot pressing. The wet α-

Al2O3/FeCl2 mixture was dried in an oven at

a temperature of 60 oC for 24 h, and then

crushed and sieved to less than 30 m in

grain size. It was observed that the color of

the dry blend was yellow-green. The dry

powder mixture was then reduced using

hydrogen gas with a flow rate of 5 L/min in

a quartz tubular reducing furnace, 4 cm in

diameter and 1.5 m in length at a

temperature of 750 oC for 15 min. The

reduced powder mixture was furnace cooled

to room temperature under a dry hydrogen

atmosphere before removal from the furnace

to the hot pressing step. The color of the

powder mixture after reduction process is

completely changed to slivery-gray,

indicating the complete reduction of ferrous

chloride and good dispersion of iron

particles throughout α-alumina.

Two techniques were used to produce

composite bulk materials. The alumina-iron

nanocomposite powders were divided for

two batches. Batch one of the produced

mixture was hot pressed at 1400 C and 27

MPa for 30 min in a graphite die of diameter

42.5 mm. The heating rate of hot-pressing

was 20 C min-1. The die was prevented

from oxidation by an inert argon atmosphere.

Batch two was heat treated in air at 700 C

for 20 min to partially oxidize the iron

particles before hot pressing to study the

effect of oxygen on the Al2O3/Fe interface

bonding and mechanical properties of the

produced composite. For comparison

monolithic alumina specimens were also

fabricated using the same method and the

same powder. Throughout the article

samples prepared from batch one is called

composite I, whereas, samples produced

from batch two is called composite II

2.2 Characterization of powders and

composites

The hot-pressed bodies were cut into

bars (5×5×30 mm) using a diamond cut-off

wheel and ground with diamond metal

bonded plates and SiC abrasive papers with

different grit up to 1500, following by

polishing on felt-cloth with diamond paste to

0.5 m surface finish. The densities of the

hot-pressed samples were measured using

Archimeds’principle in toluene, and the

theoretical density was calculated by the law

of mixture. Phase identification of powders

and the final composite was determined

using X-ray diffractometey (XRD) on a

D/Max-RB X-ray diffractrometer.

Transmission electron microscopy (TEM)

was used to measure and analyze the

powders size and morphology of the reduced

iron particles. Hardness (HV10) was

obtained with Vickers diamond indenter

using a 98 N load and a loading time of 15

sec. The harness value was taken as an

average of 10 readings. The fracture strength

of the composites was evaluated using a

three-point bending test at ambient

conditions with span 24 mm and cross head



speed 0.5 mm min-1. Microstructure

observations of the polished surfaces, the

fracture surfaces and the crack propagation

behaviour of the produced composites were

investigated using a Stereoscan 360

(Cambridge, UK) scanning electron

microscope (SEM) working at 20 Kv. The

surfaces were coated with gold using a Joel

fine coater machine (JFC-1200) to avoid

charging during the SEM observations.

Electron probe micro analysis (EPMA) was

used to analyze the distribution elements of

composite II. The fracture toughness was

measured using the indentation strength by

bending (ISB) method[27].

3. Results and Discussion:

The chemical reaction for the reduction of

ferrous chloride by hydrogen gas can be

represented as:

1...........)(

)()()( 22

gasHCl

solidFegasHsolidFeCl Heat

Based on the thermodynamics

calculation (see appendix A) and the given

data in Table 1[28], the equilibrium

temperature for reaction in Eq.1 was found

to be 615 oC (888 K). Since the reduction of

ferrous chloride by hydrogen is endothermic

reaction (H888 K = 146.23 KJ.mol-1), a

temperature higher than the calculated

equilibrium temperature is required for the

reaction to proceed in the direction of iron

formation. In the present work the

temperature of reduction chosen to be 750 oC.

Table 1 Values of the standard free energy change, enthalpy change and entropy

for FeCl2 (s), HCl (g), H2 (g) and Fe(s) [28].

Materials )( 1

298

molkJ

H o

k

)( 1

298

molkJ

G o

K

)( 11

298

kmolJ

S o

k 22 cTTcbTaCp

a 310b 510c c

FeCl2 (s) -342.25 -303.49

120.1 79.25 8.70 -4.90 ---

HCl (g) -92.31 -95.23

186.6 26.53 4.60 2.59 ---

H2 (g) 0.00 0.00

130.6 27.28 3.26 0.50 ---

Fe (s) 0.00 0.00

27.15 17.49 24.77 --- ---

The XRD profiles that were

registered for the starting mixture of -

alumina and ferrous chloride before

reduction, after reduction in a H2 gas at 750

for 15 min, and after heat treating the

reduced mixture in air at 700 oC for 20 min

are given in Fig 1. The XRD pattern before

reduction, contains only the characteristic

peaks for -Al2O3 and FeCl2.4H2O, line a in

Fig.1. After reduction at 750 C for 15 min,

The FeCl2.4H2O peaks are not observed,

whereas the peaks for -Al2O3 and Fe are

found, line b in Fig.1, indicating complete

reduction of FeCl2.4H2O phase to iron phase

according to Eq.1.



Fig.1 XRD profiles for the starting mixture of -alumina and ferrous chloride

before reduction (line a), after reduction in a H2 gas at 750 for 15 min (line b),

and after heat treating the reduced mixture in air at 700 oC for 20 min (line c).

Some iron particles that collected by

magnetic field form the reduced alumina-

ferrous chloride mixture is investigated using

TEM to determine their morphological

(particle size and shape) properties, Fig.2. As

it is shown in Fig.2, the size of the produced

iron powders in the range of 50 -110 nm and

the particles shows the spherical shape.

Fig.2 Typical morphology of the iron powders (TEM)

10 20 30 40 50 60 70 80

2, °

Inte

nsity

, Arb

itrar

y un

itsFe

Spinel

(a)

(b)

(c)

Fe2Cl2.4H2O

-Al2O3



The XRD pattern of hot-pressed

composite of the reduced mixture, composite

I, gives the same characteristic peaks that

given in line b, Fig.1, indicating there is no

reaction product between -Al2O3 and Fe

during the consolidation process. Typical

microstructure for the composite I is shown

in Fig.3. The iron areas have bright contrast

whereas, the alumina grains are dark. Iron

particles appear to be uniformly distributed

in the alumina matrix. The materials are

homogeneous in that the volume fraction of

metal is constant everywhere in the

specimen. Coalescence of the initial iron

nano-particles in the chemically synthesized

powder occurs during the thermal

consolidation and micrometer size metal

particles with a complex morphology are

formed. Nevertheless, a large amount of

finer-scale particulates have also been

retained and a wide distribution of shape and

size is observed, Fig.3 (b).

The XRD profiles that were

registered for powders of batch two, after

heat treated in air at 700 C for 20 min

shows the peaks of -Al2O3, Fe and FeAl2O4

spinel phase, as shown in Fig.1 (line c). The

same peaks are also observed after hot-

pressing. The appearance of the FeAl2O4

spinel phase in batch two after treating and

in its composite is due to the presence of

oxygen in the surrounding atmosphere.

Fig.3 (a) Low and (b) high magnification SEM photomicrographs showing the

microstructure of composite I .

The photomicrograph in Fig.4 shows

typical microstructure for the composite II.

Three distinguished regions are observed:

alumina (dark regions), iron (light regions)

and spinel (gray regions). Open porosity can

be observed at the Al2O3/FeAl2O4 and

FeAl2O4/Fe interfaces, Fig.4 (b). It was

reported that the presence of spinel phase is

expected with oxygen presence in the

environmental production operation of the

composite and its thickness depends on the

time and temperature of processing[16,31]. It

was observed in Fig.4 (b) also, some iron

particles that completely changed to the

spinal phase due to the sensitivity of the

reduced iron particles to oxygen in air during

heat treatment at 700 oC for 20 min. Hence,

the oxygen partial pressure in this region was



high enough such that the conditions for

spinel formation were satisfied. Figure 5

shows the distribution map of the constituent

elements for composite II, i.e. iron,

aluminum, oxygen as shown in Figs.5 (b),

Fig.5 (c), and Fig.5 (d), respectively. It can

be seen that the gray areas corresponding to

spinel have a depleted amount of iron and

aluminum. The spinel is associated with the

iron particles and has formed as a result of

the additional oxygen in the system. The

central region in Figure 5 (a) shows very

little porosity and any porosity that does

exist appears to be associated with the spinel

regions. The fact that most of the iron was

consumed in the process of spinel formation

in many regions suggests that the conditions

for spinel formation were not optimized

Fig.4 (a) Low and (b) high magnification SEM photomicrographs

showing the microstructure of composite II .

Fig 5. Electron probe chemical analysis showing the distribution map of the constituent

elements for the composite II; (a) same as b in Fig.4, but higher magnification (b)

iron, (c) aluminum and (d) oxygen.



Densities, mean values of hardness,

fracture strength and fracture toughness of

the alumina and composites are given in

Table 2. Relative density of composite I is

slightly higher than that of the hot-pressed

monolithic alumina. Nevertheless, the final

density of both composite and the monolithic

alumina is higher than 99.4 % of the

theoretical value. It can be concluded that

the hot-pressing technique in the present

study succeeded to consolidate a monolithic

ceramic and ceramic/metal nanocomposites

and produce nearly full dense materials.

Relative sintered density of composite II

gives a lower value around 96.5 %. This

decrease in density may be attributed to of

the presence of porosity associated with the

formation of iron aluminate spinal

phase[16,29].

The hardness values of all the

composite specimens are lower than that of

pure alumina. The lower hardness values of

the composites could be explained by

addition of ductile iron particles to the

matrix. The fracture strength of the produced

composite I is higher than that of the

alumina and the produced composite II. It is

reasonable to expect the increase of the

fracture strength with decreasing the grain

size, as suggested by Petch for brittle metals,

and by the Griffith criterion for brittle

fracture[30]. The strengthening of composite I

is, therefore, explained as being mainly

attributed to the refinement of matrix grains

by the nano-sized iron dispersion at the grain

boundary and the toughness improvement.

This results is in a good agreement with that

obtained by Sung –Tag Oh et al.[8] for the

alumina/copper system. The two composites

have been found to be tougher than the

virgin alumina matrix. Significant

improvement of fracture toughness was

observed for composite I, as shown in Table

2. Toughness of composite I is twice as high

as than that of the alumina, whereas,

toughness of composite II is improved only

by 50 % over that of the pure alumina

specimens. The lower fracture toughness of

composite II is ascribed to the lack of ductile

iron particles in the microstructure due to the

fact that they were consumed in the process

of forming the brittle spinel phase.

Table 2 Relative density and mechanical properties of the composites and the

aluminamonolithic.

Material Density

(% theoretical)

Hardness

(GPa)

Fracture strength

(MPa)

Fracture toughness

(MPa m1/2

)

Pure alumina 99.4 20.1 400 3.4

Composite I 99.6 14.8 780 8.1

composite II 96.5 15.3 470 5.1

Scanning electron micrographs of the

fracture surfaces for the composite I and the

composite II are shown in Figs.6 and 7,

respectively. As shown in Fig.6 (a) iron

particles that have been deformed plastically

can be observed in some areas, and these



particles contribute more to toughening.

However, there are also cavity sites on the

fracture surface, indicating pull out of some

iron particles. The main toughening

mechanisms in such type of composite are

crack deflection and plastic deformation of

the metal particles. Figure 8 also shows

cavity sites on the fracture surface,

indicating pull out of iron particles and

spinel phase. Pull out of iron particles

seriously restricts the plastic deformation of

the iron during the fracture of the composite

II. Microcracks could be observed on the

fracture surface of composite II, as shown in

Fig.7 (a).

Fig.6 SEM photomicrograph showing the fracture surface of composite I


showing the fracture surface of composite II

However, very little iron particles that

have been deformed plastically can be

observed, and these particles slightly

improve the toughness. The toughening

mechanisms, which are observed to occur in

this composite, include mainly the crack

deflection mechanism. In the region where

spinel phase exists, the indentation crack

goes through the spinel phase, or along the

interface between the iron and the spinel as

shown in Fig.8 indicating poor bonding at

the FeAl2O4/Fe and FeAl2O4/Al2O3

interfaces. Therefore, it can be concluded

that, the spinel regions are detrimental to the

toughness of the composite II, as they would

provide a preferential fracture path for a

propagating crack producing a more brittle

material. The poor bonding between

spinel/alumina and spinel/metal is also

observed in other ceramic/metal systems[16,

29]. Trumble and Ruhle[29], in a study of

spinel interphase formation at diffusion-



bonded Al2O3/nickel interfaces, have

observed the existence of physical gaps

along the spinel layer and, thus, proposed

that this is the origin of the weakness of the

spinel/nickel interface. In contrast to their

observation, Sun and Yeomans[31], reported

that the spinel/nickel interface is quite

intimate, and no physical gap has been

observed. In the present work, both

phenomenon are observed between the

spinel/alumina and the spinel/iron interfaces.

Thus, the spinel/iron interface may be

intrinsically weak, or the weakness may be

due to the residual thermal stress because of

the difference in coefficient of thermal

expansion (CTE) between spinel and iron.

Because the CTE of spinel is almost the

same as that of alumina[32], thermal stresses

at the spinel/iron and Al2O3/iron interfaces

should be very similar. Thus, the spinel/iron

interface may be considered to be

intrinsically weak. Thick layer of spinel has

a detrimental effect on the mechanical

properties in many systems[29, 31].


of indentation cracks propagation in the composite II

The effect of a very thin layer of spinel

(such as one atomic layer) on the bonding

between iron and Al2O3 is unclear and

difficult to control, however some authors

consider it to be beneficial for the bonding

between nickel and alumina in the

alumina/nickel composite[33]. In fact, the

phenomena of the spinel phase formation

and the factors affecting are not well

understood till now and need more research.

Moreover, it is difficult to control the

thickness of spinel phase in all the areas of

the hot pressed specimens, because of the

oxygen partial pressure gradient from the

outer surface to the inner surface of the

specimen.

4. Conclusions (1) A novel processing route consists of

mixing -alumina powder with

ferrous chloride solution followed by

drying and reduction at 750 oC for 15

min in a dry hydrogen atmosphere

successfully produced -alumina-

iron powder mixture, where nano-

sized iron particles are

homogenously and highly distributed

in the alumina matrix.

(2) Hot pressing of the formed powder

mixture at 1400 C and 27 MPa for

30 min in a graphite die produce

ceramic-metal nanocomposite with

fracture strength and fracture



toughness that are twice as high as

those of the monolithic alumina. In

other words, this technique offers a

new nano composite material with

fracture strength of 780 MPa and

fracture toughness of 8.1 MPam1/2,

that can be the perfect candidate in

many structural and engineering

applications.

(3) Heat treatment of the -Al2O3-Fe

powder mixture in air at 700 oC for

20 min produces powder mixture

mainly consists of -Al2O3, Fe and

FeAl2O4 spinel.

(4) Hot pressing of the -Al2O3-Fe-

FeAl2O4 powder mixture produces

composite with fracture strength and

fracture toughness that are slightly

higher than those of the monolithic

alumina.

(5) The presence of spinal phase,

FeAl2O4, as thick layer around the

iron particles in the alumina matrix

has a detrimental effect on interfacial

bonding between iron and alumina

and the fracture properties of the

composite.

Appendix : Calculation of reduction

temperature of ferrous chloride: Based on the thermodynamics

aspects and from the given data in Table 1,

the free energy change (Go) for the

reduction of ferrous chloride to iron

according to Eq.1 can be calculated using

Eq. 2 to be: 113.03 KJ.mol-1

)2(22

298o

Fe

o

FeCl

o

HCl

o

Feko GGGGG

This means that the reaction is not

spontaneous and need energy to start. The

enthalpy change (Ho) for the reduction

reaction gives a value of 157.63 KJ.mol-1

using Eq.3:

)3(222298

o

H

o

FeCL

o

HCL

o

Fe

o

k HHHHH

and the entropy change gives a value of 149.65 J.mol-1.K-1 using Eq.4.

)4(222298

o

H

o

FeCL

o

HCL

o

Fe

o

k SSSSS

Change of specific heat at constant pressure (CP) can be calculated using Eq.5 to be:

o

H

o

FeCL

o

HCL

o

Fe

o

k CpCpCpCpCp22

2298

= -35.98 + 0.02201 T + 9.578 10-5 T-2 (5)

At the reduction temperature T:

)6(298

298 dtCHHT

K

P

o

KT

)7(298

298 dtT

CSS

T

K

Po

KT

For the reduction of ferrous chloride by

hydrogen to start G in the general form of

thermodynamic second law (Eq.8) should be

less than zero and HT has a positive value .

)8(TT STHG



At G = 0 and substituting in Eq.8 using Eqs 6 and 7, then:

)9(0)()(298

298

298

298

dtT

CSTdtCH

T

K

Po

K

T

K

P

o

K

On solving Eq.9 by substituting the value of

CP (Eq.5) and integrating the equation as a

function of T, the theoretical value of the

reduction temperature of ferrous chloride to

iron particles is obtained to be 615 oC.

--------------------------------------------------------------------------------------------------------------------------------

دام مسحوق طريقة مبتكرة إلنتاج المواد المركبة النانومترية ذات األرضيه السيراميكيه باستخ

أكسيد األلومنيوم ومحلول كلوريد الحديدوز كمواد أولية صالح محمد مفتاح، محمد محمد عبد المنعم السيد

كلية الهندسة ـ جامعة سبها --------------------------------------------------------------------------------------------------------------------------------

ملخصال

سبها خواص جديدة مثل مقاومتها أوضحت األبحاث الحديثة أن إضافة المواد الفلزية النانومتريه الى المواد السيراميكية يك

لالنهيار المفاجئ وذلك بتحسين المتانة مع الحفاظ على خواصها األصيلة مما يفتح مجاالت إستخدام جديدة للمواد المركبة

الناتجة. وتهدف هذه الدراسة إلى تحضير و إنتاج المواد المركبة النانومترية ذات األرضية السيراميكية بطريقة اختزال منتقاه

لخليط مسحوق أكسيد األلومنيوم مع محلول كلوريد الحديدوز والذى يتم فيه إختزال األخير بواسطة الهيدروجين الجاف الى حديد

بالحجم من الحديد. وأختيرت درجة %20بحجم حبيبات فائقة الدقة )نانومتر( وتم الخلط على أساس إنتاج مواد مركبه تحوي

دقيقه. هذا وتم إنتاج 15ناءا على حسابات الديناميكا الحرارية وتم اإلختزال عند زمن درجه مئوية ب 750حرارة اإلختزال

جو خامل عند درجة حرارة فينوعين من المواد المركبة: النوع األول تم كبس الخليط الناتج من اإلختزال مباشرة على الساخن

النوع الثانى من المواد المركبة تم معالجة الخليط الناتج من فيميجابسكال, و 27دقيقة و ضغط 30درجة مئوية وزمن 1400

دقيقة و ذلك قبل كبسه على الساخن بهدف دراسة 20درجة مئوية و لمدة 700الهواء عند درجة حرارة فياإلختزال حراريا

ميكانيكية للمواد المركبة الناتجة. تأثير األكسجين على قوة الربط بين الحديد و أكسيد األلومنيوم وبالتالي تأثيره على الخواص ال

( XRDهذا ولتقيم سلوك وخواص المخلوط الناتج من اإلختزال وكذا المواد المركبة تم استخدام األشعة السينية )

( وتم رصد تواجد عناصر األلومنيوم TEM( والميكروسكوب اإللكتروني النافذ )SEMوالميكروسكوب اإللكتروني الماسح )

إختبار EPMAالمواد المركبة الناتجة بواسطة جهاز التحليل اإللكتروني ) فين والحديد واألكسجي ( هذا وتم أيضا

الخواص الميكانيكية للمواد المركبة. ولقد أوضحت النتائج أن طريقة اإلنتاج المقترحة )خلط ثم اختزال ثم كبس على الساخن(

بالحجم( فائقة الدقة ومتجانسة التوزيع مع %20تحوى مواد فلزيه )إنتاج مواد مركبه ذات أساس سيراميكى و فينجحت

تحسين المتانة و مقاومة الكسر كما وجد أيضا أن وجود تفاعل كيميائي بين أكسيد الحديد و أكسيد األلومنيوم وتكون الطور

4O2FeAl ة الناتجة.صورة طبقه سميكة يضعف المتانة و مقاومة الكسر ويعجل بانهيار المواد المركب في --------------------------------------------------------------------------------------------------------------------------------

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