Nitriding of dilute Mo-Ti alloys at a low temperature of 1373 K

Masahiro Nagae, Shigetoshi Okada, Makoto Nakanishi, Jun Takada, Yutaka Hiraoka, Yoshito Takemoto, Moritaka Hida, Hideyuki Kuwahara, Myoun Ki Yoo

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Abstract

For Mo-0.5 mass% Ti and pure Mo alloy nitrided in a NH3 gas at a relatively low temperature of 1373 K, microstructural observations through optical and transmission electron microscopes, X-ray diffraction analysis and hardness measurements were carried out. A surface nitriding layer with very high hardness of approximately Hv ∼ 1800 consisted of two Mo-nitride regions: an outer one of γ-Mo2N and an inner one of β-Mo2N. The inward diffusion of nitrogen is a rate-controlling process in the growth of the surface nitriding layer. In Mo-Ti alloy additionally an internal nitriding layer with relatively high hardness of Hv ∼ 800 was formed beneath the surface nitriding layer. Such high hardness in the internal nitriding layer was found to result from the uniform dispersion of extremely fine plate-like particles of titanium nitride. The particles are approximately 0.4 nm thick and have coherent strain field in the matrix.

Original languageEnglish
Pages (from-to)127-132
Number of pages6
JournalInternational Journal of Refractory Metals and Hard Materials
Volume16
Issue number2
Publication statusPublished - 1998

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ASJC Scopus subject areas

  • Metals and Alloys

Cite this

Nagae, M., Okada, S., Nakanishi, M., Takada, J., Hiraoka, Y., Takemoto, Y., Hida, M., Kuwahara, H., & Yoo, M. K. (1998). Nitriding of dilute Mo-Ti alloys at a low temperature of 1373 K. International Journal of Refractory Metals and Hard Materials, 16(2), 127-132.