Prakt. Met. Sonderband 52 (2018) 333
Reaction Phase Formation Kinetics in a TiC-Steel-MMC during
Solid-State Consolidation and Heat Treatment
Ady,
i J. Pérnbacher*, S. Marsoner*, H. Leitner**, G. Ressel*
"Clemens * Materials Center Leoben Forschung GmbH, Roseggerstralle 12, 8700 Leoben
** .yoestalpine Béhler Edelstahl GmbH & Co KG, Mariazeller-Stralle 25, 8605 Kapfenberg
Her, 10.
ayy ~~ ABSTRACT
The incorporation of hard particles in steel matrices to advance their mechanical properties
iechnal, 247 is a well-established concept. Particular titanium carbide reinforcements are extensively
used due to their decent bonding behavior towards steel matrices and high hardness.
3. Although they are in general described as stable during solid-state manufacturing, recent
9.5% findings showed that this is not necessarily the case and reaction phases can form.
This study deals with the formation kinetics of such reaction phases in a powder
metallurgical produced composite based on a heat treatable steel matrix reinforced with
Laer 10 vol.% titanium carbide. The amount of reaction phase formed in samples hot isostatically
pressed for 3.5, 6.0 and 24 h was investigated by quantitative image analysis of scanning
Aool. Cryst. electron microscope images and semi-quantitative x-ray diffraction analysis. It was found by
both methods that with increasing consolidation time, also the amount of reaction phase
increases. This means that pressing time has an influence on microstructure and potentially
mechanical properties of the composite. -
1. INTRODUCTION
Steel-based metal matrix composites (MMCs) offer exceptional mechanical properties such
as high wear resistance and specific modulus [1]. Especially the combination with particulate
titanium carbide (TiC) has been investigated extensively due to TiC’s high hardness and
excellent bonding behavior towards steel matrices. Such composites can be produced by
several different processes such as in-situ techniques, liquid metal particulate mixing or via
powder metallurgical (PM) route. PM techniques offer the advantage of easy variability
regarding TiC content and particulate size, and are thus most often applied [2].
Consolidation of pre-blended powders can either be done by sintering in the presence of a
liquid phase (e.g. super-solidus liquid phase sintering) or via solid-state techniques such as
hot isostatic pressing (HIP). While for pressureless sintering no special equipment is
needed, infrastructure expenses for HIP systems are very high, and thus less literature is
available. It is well known that TiC dissolves in the presence of a liquid phase and forms a
core-rim structure, which incorporates carbide forming elements from the steel matrix [3].
Conversely, TiC is generally reported as stable in steel matrices when pure solid-state
production techniques are applied and matrix carbides are fully dissolved at processing
temperature [4, 5]. However, other studies of the authors show that TiC is not necessarily
stable during solid-state production [6]. Moreover, reaction phase formation of TiC in other
matrix systems such as molybdenum have also been reported for samples prepared by
solid-state techniques [7].
