642
M. C. Bouleklab et al.
recognized method of the “cold” treatment of solid powder composites [11–16]. The
materials thus obtained reveal new, interesting properties, which determine the longterm interest in their manufacture and research in comparison with the materials
obtained in another way [17–20]. A quantitative thermodynamic explanation for the
formation of solid solutions of immiscible elements by mechanical alloying has also
been proposed [21].
The mechanical alloying of copper is also a way of developing high-strength
alloys maintaining high electrical and thermal conductivity. Some examples are Cu–
Fe, Cu–Ta, Cu–V, and Cu–W [20] composites. The Fe–Cu system is nearly immiscible in equilibrium at room temperature and up to 600 °C and it has a positive
heat of mixing [20]. That is why the creation of metastable single-phase solid solutions of nanocrystalline sizes of grains by mechanically alloying the Fe–Cu powders
has been extensively studied [20]. Interestingly, the Fe–Cu composites with layered
microstructure were also produced, where nanoscaled Fe clusters were dissolved
in the Cu matrix [20]. The results of a large number of studies have confirmed the
possibility to make metastable Fe–Cu composites by the MA method [22–24]. The
potential to extend the mutual solubility of Fe and Cu due to mechanical alloying has
been widely reported. The formation of face-centered cubic (fcc) single-phase solid
solutions was observed for Fe x Cu 1−x alloys with a Fe content x < 60 at.%, two-phase
alloys consisting of an fcc and a body-centered cubic (bcc) phase were formed for
an Fe content of 60 < x < 80 at.%, and bcc single-phase solid solutions have been
obtained for an Fe content of x > 80 at.%. It was observed that the mixing occurs on
the atomic level in the milled alloys [20] and the crystallite size in the milled powders
was reported to be ~20 nm or smaller. Decomposition of the unstable Fe–Cu solid
solutions occurred due to annealing treatments was also reported [20]. It was found
that many structural defects were incorporated in a material during severe plastic
deformation) processes, which was accompanied with a higher dislocation density, a
higher vacancy concentration, and the continuous formation of new grain boundaries
[20].
Various additives can influence both properties and temperature behavior of the
Fe–Cu composites. Thus, the dimensional changes in ferrous sintered compacts are
influenced by several factors, including particle size, density, composition, sintering
time and temperature, cooling rate, and microstructure. Reduced particle size and
increased sintering time and temperature can be used to reduce dimensional change.
Given a set base iron and sintering conditions, factors such as composition and
cooling rate play an important role on microstructure, dimensional change, and
mechanical properties. The most widely used additives to P/M iron are graphite
and copper. Separately, copper and graphite additions cause growth in the sintered
compact [25].
Additives of various carbon forms cause different effects on the intermetallic
composites. Uncontrolled impurities of carbon materials could be various carbon
forms aroused under milling due to the by-products of the destruction of the organic
compounds. The latter could be used in the process of milling and specifically as
lubricants [26, 27]. That is why the role of carbon materials in the MA processes and
in determining the properties of the resulting composites was a special subject of
research. As a result, it was shown that the kinetics of solid-state reactions, as well as
M. C. Bouleklab et al.
recognized method of the “cold” treatment of solid powder composites [11–16]. The
materials thus obtained reveal new, interesting properties, which determine the longterm interest in their manufacture and research in comparison with the materials
obtained in another way [17–20]. A quantitative thermodynamic explanation for the
formation of solid solutions of immiscible elements by mechanical alloying has also
been proposed [21].
The mechanical alloying of copper is also a way of developing high-strength
alloys maintaining high electrical and thermal conductivity. Some examples are Cu–
Fe, Cu–Ta, Cu–V, and Cu–W [20] composites. The Fe–Cu system is nearly immiscible in equilibrium at room temperature and up to 600 °C and it has a positive
heat of mixing [20]. That is why the creation of metastable single-phase solid solutions of nanocrystalline sizes of grains by mechanically alloying the Fe–Cu powders
has been extensively studied [20]. Interestingly, the Fe–Cu composites with layered
microstructure were also produced, where nanoscaled Fe clusters were dissolved
in the Cu matrix [20]. The results of a large number of studies have confirmed the
possibility to make metastable Fe–Cu composites by the MA method [22–24]. The
potential to extend the mutual solubility of Fe and Cu due to mechanical alloying has
been widely reported. The formation of face-centered cubic (fcc) single-phase solid
solutions was observed for Fe x Cu 1−x alloys with a Fe content x < 60 at.%, two-phase
alloys consisting of an fcc and a body-centered cubic (bcc) phase were formed for
an Fe content of 60 < x < 80 at.%, and bcc single-phase solid solutions have been
obtained for an Fe content of x > 80 at.%. It was observed that the mixing occurs on
the atomic level in the milled alloys [20] and the crystallite size in the milled powders
was reported to be ~20 nm or smaller. Decomposition of the unstable Fe–Cu solid
solutions occurred due to annealing treatments was also reported [20]. It was found
that many structural defects were incorporated in a material during severe plastic
deformation) processes, which was accompanied with a higher dislocation density, a
higher vacancy concentration, and the continuous formation of new grain boundaries
[20].
Various additives can influence both properties and temperature behavior of the
Fe–Cu composites. Thus, the dimensional changes in ferrous sintered compacts are
influenced by several factors, including particle size, density, composition, sintering
time and temperature, cooling rate, and microstructure. Reduced particle size and
increased sintering time and temperature can be used to reduce dimensional change.
Given a set base iron and sintering conditions, factors such as composition and
cooling rate play an important role on microstructure, dimensional change, and
mechanical properties. The most widely used additives to P/M iron are graphite
and copper. Separately, copper and graphite additions cause growth in the sintered
compact [25].
Additives of various carbon forms cause different effects on the intermetallic
composites. Uncontrolled impurities of carbon materials could be various carbon
forms aroused under milling due to the by-products of the destruction of the organic
compounds. The latter could be used in the process of milling and specifically as
lubricants [26, 27]. That is why the role of carbon materials in the MA processes and
in determining the properties of the resulting composites was a special subject of
research. As a result, it was shown that the kinetics of solid-state reactions, as well as