Selective laser melting of in situ TiN–Ti₅Si₃ composites with RE–Si–Fe addition: comparative study

Abstract

A comparative study was conducted to investigate the influence of rare earth (RE)–Si–Fe addition on the microstructures and tribological properties of in situ TiN–Ti₅Si₃ composites prepared by selective laser melting (SLM). With the addition of 3 wt-% RE–Si–Fe, the shape of in situ TiN reinforcing particles became rounded and smoothened, the particle size was refined and the dispersion state was homogenised. Relative to TiN–Ti₅Si₃ composites without RE addition, the average friction coefficient of SLM processed RE containing composites decreased from 0·85 to 0·55, and the resultant wear rate decreased from 3·79×10⁻⁴ to 2·65×10⁻⁴ mm³ N⁻¹m⁻¹. Metallurgical functions of the RE elements in improving the SLM processability and the resultant wear performance of in situ composites were elucidated.

Keywords:

• Composites
• Titanium silicide
• Rare earth
• Wear and tribology
• Selective laser melting

One of the authors (D. D. Gu) gratefully appreciates the fellowship of the Alexander von Humboldt Foundation for sponsoring his research stay in Germany. The present work is financially supported by the National Natural Science Foundation of China (grant no. 51054001), the Natural Science Foundation of Jiangsu Province (grant no. BK2009374), the Aeronautical Science Foundation of China (grant no. 2010ZE52053) and the NUAA Research Funding (grant no. NS2010156).