Nanocomposites and nanomaterials

Compatibility of the non-metallic structure modifiers nanoscale particles with common filler alloys of aluminum welding
Shcheretskyi V.O.1, Demjanov O.I.2, Yi Jianglong 3
1 Physico-technological Institute of metals and alloys of the NAS of Ukraine, bul. Vernadskogo, 34/1, Kyiv, Ukraine. 
E-mail: shcheretskyi@nas.gov.ua
2 E.O. Paton Electric Welding Institute the NAS of Ukraine, 1 Kazymyr Malevych St., Kyiv 03150 Ukraine.
3 Guangdong Welding Institute (China-Ukraine E. O. Paton Institute of Welding) of GDAS, China.

The work discovers the features of application promising nanoscale non-metallic microstructure modifiers (particles TiC, WC, TiB2) of a weld in aluminum alloys welding process. The particles applicability was assessed from the standpoint of thermodynamic stability into melts of industrial welding alloys of Al-Mg and Al-Si alloying systems containing Cu, Fe, Zn, Mn, Ti as alloying elements. It is shown that despite its relative instability, nanoscale TiC particles can be used as modifiers of aluminum alloys of the Al-Mg system, the presence of silicon reduces the stability of titanium carbide in the aluminum melts and therefore it`s presence is not desirable, the titanium, on the contrary, increases the TiC carbide stability. WC particles can be successfully used to modify the microstructure of the Al-Si alloy system, while the presence of silicon increases their stability in the melt. Particles of titanium diboride TiB2 is the most stable compound of the studied particles, its insignificant modifying effect on aluminum alloys is compensated by its resistance to aluminum melts at significant overheating (above 1100 ° С).
It was discovered that welding aluminum alloys of the 4th series (Al-Si) containing 5 and more weight. % of silicon are promising materials for hardening with highly dispersed particles of tungsten carbide (WC), since they increase the stability of silicon-modifying particles. The presence of silicon up to 1 wt % in the Al-TiC system practically does not affect the interaction of titanium carbide particles with aluminum melts. An increase in silicon concentration leads to the formation of the titanium silicides (TiSi, TiSi2) from the liquid phase, a further increase in the silicon content only enhances the interaction in this system.
Acknowledgment
This work was supported by the project of Inter-Governmental S&T Cooperation (CU03-08), and the technical project of Guangdong (20180508).