Nitrogen-Induced Formation of Nano-Structured Precipitations in the Ti-W-C-N System

Alexander Eder; Rudolf Königshofer; Walter Lengauer

doi:10.4028/www.scientific.net/DDF.237-240.1121

Paper Titles

Scaling Properties of the Diffusion Process Underlying the Havriliak-Negami Relaxation Function
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Sedimentation of Substitutional Solute Atoms in Intermetallic Compound of Bi-Pb System under Ultra-Strong Gravitational Field
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Long-Term, Cyclic Oxidation Behaviour of Alumina- and Chromia-Forming Alloys
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Chemical and Physical Interactions of Si-Rich Steel Substrates during Hot Dipping Experiments in a Molten Al-(25 wt%)Si Alloy
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Nitrogen-Induced Formation of Nano-Structured Precipitations in the Ti-W-C-N System
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Mechanisms of Diffusion and Dissociation of E-Centers in Silicon
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MD Simulation Study of B1-B2 Phase Transition of KCl under High Pressure: Effects of Defects
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Auger Electron Spectroscopical Investigation of Interfacial Segregation in the Cu-Bi System
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Phase Transformations in ε-/γ'-Iron Nitride Compound Layers in the Temperature Range of 613 K - 693 K
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Nitrogen-Induced Formation of Nano-Structured Precipitations in the Ti-W-C-N System

Abstract:

A general trend in the field of hardmetals is to achieve a refinement of the microstructures, usually by using sub-micron powders as raw materials. In this study, an alternative route to produce fine structures within the fcc hard phase (W,Ti)(C,N) is investigated: nitrogen indiffusion into (W,Ti)C leads to precipitation of tungsten-rich phases. The mechanism of precipitation (lamella- and labyrinth-like structures with a size of 100-400nm) is thought do be discontinuous segregation on the one hand and spinodal decomposition on the other hand. Hot-pressed (W,Ti)(C,N) samples of different compositions were annealed at different temperatures and C activities in high-pressure N2 atmosphere. The composition and resulting structures of the precipitates were correlated with composition of the (W,Ti)(C,N) phase as well as with annealing conditions. An outlook of a possible application of the observed phenomena to powder particles is given to achieve micron-sized particles of this hard phase with nanometer-sized structures as a raw material for fine-grained hardmetals.