Journal of University of Science and Technology Beijing
Volume 14, Number 6, December 2007, Page 1
Corresponding author: Guoqing Xiao, E-mail: xiaoguoqing@xauat.edu.cn Also available online at www.sciencedirect.com
Materials
Dissolution-precipitation mechanism of self-propagating
high-temperature synthesis of TiC-Cu cermet
Guoqing Xiao
1)
, Feng Duan
1)
, Gang Zhang
1)
, and Quncheng Fan
2)
1) School of Materials Science and Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China
2) State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
(Received 2006-12-30)
Abstract: A mechanism of self-propagating high-temperature synthesis (SHS) of TiC-Cu cermet was studied using a combustion
front quenching method. Microstructural evolution in the quenched sample was observed using a scanning electron microscope
(SEM) with energy dispersive X-ray (EDX) spectrometry, and the combustion temperature was measured. The results showed that
the combustion reaction started with a local formation of a Ti-Cu melt and could be described with a dissolution-precipitation me-
chanism, namely, Ti, Cu, and C particles dissolved into the Ti-Cu solution and TiC particles precipitated in the saturated Ti-Cu-C liq-
uid solution. The local formation of the Ti-Cu melt resulted from a solid diffusion between the Ti and Cu particles.
Key words: TiC-Cu cermet; self-propagating high-temperature synthesis; microstructural evolution; synthesis mechanism; combus-
tion front quenching method
1. Introduction
As a potential high-temperature electric conduct
material, TiC-Cu cermet is very attractive for a wide
range of potential applications because of its good
high-temperature electrical conductivity, mechanical,
and wear properties
[1-2].
In the past, TiC-metal cermet was prepared using
powder metallurgy
and casting technologies [3], where
TiC particles were directly incorporated into solid or
liquid matrices, respectively. Recently, a
self-propagating high-temperature synthesis (SHS)
technique, also termed combustion synthesis, is used
for the preparation of TiC-Cu cermet from Ti, C, and
Cu powders by some investigators
[4-5] because of its
advantages, such as simple equipment, the easily per-
formed process, low energy consumption, and non-
polluting traits.
These years, wide investigation on the SHS of met-
al matrix composites reinforced with TiC has been
carried out [4-11]. Zarrinfar [4] investigated the SHS
of TiC-Cu cermet from the elemental powder mixture
with the ratio of C/Ti from 0.4 to 1, and found that the
carbides produced differed from that predicted from
the initial SHS reactant mixture, and in the course of
the reaction, there were Ti-Cu intermetallics existing
and persisted as a final reaction product. Zarrinfar [5]
also prepared TiC-Cu master-alloys using the SHS
method, the experimental results indicated that
TiC-Cu master-alloys were produced by the reaction
synthesis of elemental powder mixtures, decreasing
the C/Ti ratio improved the distribution of the carbides
in the master-alloys. Till date, however, the mechan-
isms of combustion synthesis of TiC-Cu cermet are
not reported.
Observation of the microstructural transitions dur-
ing a combustion synthesis will be of benefit to the
understanding of the synthesis mechanism. Using a
combustion front quenching method (CFQM), Roga-
chev et al. [12] have observed the microstructural
transitions on Ti-C and Ti-B specimens. In the speci-
mens, the combusting waves self-propagating were
quenched, thus the initial, the intermediate, and the
end-reaction products were frozen in the quenched
sample, and then the microstructural evolutions in the
quenched samples were analyzed with scanning elec-
tron microscope (SEM) and energy dispersive X-ray
spectrometry (EDX).
In the present work, the mechanism of combustion
synthesis of TiC-Cu cermet was studied using the
CFQM method. The microstructural evolution in the
quenched specimen was observed and analyzed with
SEM and EDX, and the combustion temperature of
the reaction was measured. Also, the phase constituent
of the combustion-synthesized product was inspected
by X-ray diffraction (XRD). On the basis of these ex-