Anisotropic Phase Transformation Mechanism on Coarse-Grained and Fine-Grained Pure Titanium at Low-Temperature Plasma Nitriding
The nitriding process of the coarse-grained and fine-grained pure titanium proceeded by multidirectional forging technique has been investigated at temperatures of 623, 673, and 723 K. The process was carried out by high-density radiofrequency-direct current plasma combined with a rectangular hollow...
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| Format: | Article |
| Language: | English |
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G. V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine
2022-03-01
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| Series: | Успехи физики металлов |
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| Online Access: | https://ufm.imp.kiev.ua/en/abstract/v23/i01/090.html |
| Summary: | The nitriding process of the coarse-grained and fine-grained pure titanium proceeded by multidirectional forging technique has been investigated at temperatures of 623, 673, and 723 K. The process was carried out by high-density radiofrequency-direct current plasma combined with a rectangular hollow cathode device. The result obtained is a significant increase in surface hardness with increasing holding temperature. The surface hardness increases due to forming a surface layer composed of δ-Ti2N, ε-Ti2N and TixNx observed from x-ray diffraction results. This paper explains the mechanism of surface layer formation. We also observed anisotropic phase transformation of titanium nitride through the right shift of the x-ray diffraction peaks. Diffused nitrogen atoms during the nitriding process cause a change in crystal orientation through structural transformation of the metastable δ-Ti2N to the stable ε-Ti2N. The structural reconstruction will continue by forming TixNx to achieve stoichiometric equilibrium. More compacting of the surface microstructure is also obtained by increasing nitriding temperature. |
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| ISSN: | 1608-1021 2617-0795 |