Nitriding behaviour of Mg-Li alloy with surface mechanical nano-alloying pretreatment

ABSTRACT

The thick titanium nitrides coating was fabricated on LZ91 alloy by surface mechanical nano-alloying (SMNAT) combined with gas nitriding. Experimental results showed that a nanostructured titanium coating with thickness of 50–80 μm was formed on surface of LZ91 alloy by SMNAT with pure titanium powders for 30 min. By adding of the aluminium powders into titanium powders during the SMNAT, a thicker Ti-Al composite coating with improved continuity and uniformity was obtained. After nitriding at 450°C, the whole Ti and Ti-Al coating were successfully nitrided. The surface layer of nitrided Ti coated sample is mainly composed of TiN, Ti₂N, TiN_0.3, TiN_0.61 and Ti₄N_2.33 phases and the surface layer of nitrided Ti-Al coated sample is composed of Ti₂N, TiN_0.9, TiN_0.3, Ti₄N_2.33, AlN, Ti₃Al₂N₂ and AlTi₂N phases. The hardness measurements demonstrated that the surface hardness of nitrided Ti coated and nitrided Ti-Al coated samples reached to 634 and 734 HV, respectively.

KEYWORDS:

• Mg-Li alloy
• titanium nitrides coating
• surface mechanical nano-alloying
• nitriding
• hardness

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (51701057), the Fundamental Research Funds for the Central Universities (JZ2018HGTB0265), the Fund of Anhui Kelante Co., Ltd (W2020JSKF0061), the Industrial Guiding Fund of Changfeng County and Hefei University of Technology (JZ2019QTXM0281), and the Fund of Anhui Wanan Co., Ltd (W2019JSKF0210).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Fundamental Research Funds for the Central Universities: [Grant Number JZ2018HGTB0265]; National Natural Science Foundation of China: [Grant Number 51701057]; Fund of Anhui Kelante Co.Ltd (W2020JSKF0061); Anhui Wanan Co.Ltd: [Grant Number W2019JSKF0210]; Industrial guiding fund of Changfeng county and Hefei University of Technology: [Grant Number JZ2019QTXM0281].