Journal of University of Science and Technology Beijing
Volume 14, Number 1, February 2007, Page 1
Corresponding author: Farid Akhtar, E-mail: Faridmet22@hotmail.com
Sintering behavior, microstructure, and properties of TiC-FeCr hard alloy
Farid Akhtar
1,2)
, Shiju Guo
1)
, Jawid Askari
1)
, and Jianjun Tian
1)
1) Material Science and Technology School, University of Science and Technology Beijing, Beijing 100083, China
2) Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore, Pakistan
(Received 2006-03-02)
Abstract: TiC based cermets were produced with FeCr, as a binder, by conventional P/M (powder metallurgy) to near >97% of
theoretical density. Sintering temperature significantly affects the mechanical properties of the composite. Sintering temperature of
>1360C caused severe chemical reaction between TiC particles and the binder phase. Optimum mechanical properties were found
with the composite sintered at 1360C for 1 h. In the TiC-FeCr cermets, the mechanical properties did not vary linearly with the carbide
content. Optimum mechanical properties were found in the composite containing 57wt% TiC reinforcement, when sintered at 1360C
for 1 h. Use of carbon as an additive enhanced the mechanical properties of the composites. Cermets containing carbon as an additive
with 49wt% TiC exhibited attractive mechanical properties. The microstructure of the developed composite contained less or no de-
bonding, representing good wettability of the binder with TiC particles. Homogeneous distribution of the TiC particles ensured the
presence of isotropic mechanical properties and homogeneous distribution of stresses in the composite. Preliminary experiments for the
evaluation of the oxidation resistance of FeCr bonded TiC cermets indicate that they are more resistant than WC-Co hardmetals.
Key words: powder technology; hard alloy; sintering; reinforcement; mechanical property
1. Introduction
TiC reinforced cermets have great hardness and re-
sistance to corrosion and oxidation [1-2]. Ideally, TiC
based cermets display a combination of physical
properties that combine the hardness of the TiC phase
and the toughness of the metallic base matrix. There is
a significant interest in developing TiC reinforced
Fe/Steel matrix, mainly to produce a combination of
hardness with improved toughness and to achieve sig-
nificant cost reductions [3-6].
The binder phase is an important constituent of the
cermet and strongly influences the mechanical, wear
and corrosion properties of cermets [7-8]. Various
binders have been used to produce TiC base cermets to
refine and enhance their properties and applications.
One of the original approaches in TiC base cermets is
to use a suitable binder material with TiC reinforce-
ments. Al, Ni, NiCr, NiMo, and various types of steel
have been used as binders in TiC base cermets [7-11].
In this study, the P/M fabrication of TiC reinforced
FeCr cermets is reported. P/M (powder metallurgy) is
currently an acceptable technique for the development
of TiC base cermets. Microstructure, mechanical and
oxidation properties of the cermets are studied.
Moreover, effect of addition of carbon as an additive on
the properties and microstructure is also discussed.
2. Experimental
TiC-xFeCr composites were produced through
conventional press and sinter P/M. P/M has been uti-
lized for years as a low-cost fabrication method for
producing near-net-shape composites; therefore, P/M
may be a cost-effective method for producing titanium
carbide-matrix cermets. P/M technology has been se-
lected as the processing method, in part because of the
simplicity associated with the incorporation of a hard
phase into a metal phase through the blending of
powders, and then pressing and sintering. P/M
processing can use wide range of reinforcement vo-
lume fraction and make distribution of embedded par-
ticles uniform. In addition extensive metal-ceramic
reactions can be avoided.
TiC powder and elemental powders of Fe and Cr
were mixed and wet milled for 72 h. The milled
powders were uniaxially pressed into cylindrical
compacts (5 mm in height and 37.5 mm in diameter)
under a pressure of 550 MPa. Sintering of all prepared
samples was performed within a high temperature va-
cuum furnace. The sintering cycle applied to the sam-
ples was as follows: samples were heated to 1000C at
a rate of 10C/ min and held at 1000 C for 10 min.
Subsequently the samples were heated to various sin-
tering temperatures of 1300, 1330, 1360, and 1400C at