Remarkable improvement in strength and ductility of Al-Cu foundry alloy by submicron-sized TiC particles

The Al-4.5Cu alloy reinforced by submicron-sized TiC particles (TiCp) was fabricated by initially in-situ synthesizing Al-5TiC master alloy, and then incorporating different contents of master alloy into the Al-4.5Cu alloy melt. The microstructural evolution and tensile properties of TiCp/Al-4.5Cu composites have been studied. The results indicated that submicron-sized TiCp with an average size of 190.9 nm were formed and distributed uniformly in the Al-5TiC master alloy, and the interface between TiCp and Al was well-boned and clean. The dendritic microstructure was changed into equiaxed in the composite, and the average grain size was evidently refined from 490 mu m to 43 mu m with the TiCp content up to 0.5 wt%. Moreover, the TiCp addition obviously refined the theta ' precipitates and increased their number density of as-aged TiCp/Al-4.5Cu composites. With the increasing TiCp addition, both strength and ductility of the composite were firstly increased and then decreased, and the 0.5TiC(p)/Al-4.5Cu composite showed the optimal tensile properties, in which the tensile strength, 0.2% yield strength and elongation were simultaneously improved from 271 MPa, 162 MPa and 9.8% to 388 MPa, 212 MPa and 23.7%, with the increment of 43%, 31% and 142% as compared with Al-4.5Cu base alloy, respectively. The improvement of strength was mainly attributed to grain refinement, enhanced precipitation strengthening of theta ' phase, and Orowan strengthening and CTE strengthening introduced by TiC particles.

Automated summary

By adding submicron-sized TiC particles (TiCp) into the Al-4.5Cu alloy, the microstructural evolution and tensile properties of the composite were significantly improved. The addition of TiCp refined the grain size, increased the density of precipitates, and enhanced the tensile strength and ductility of the composite within a certain range. The 0.5TiC(p)/Al-4.5Cu composite exhibited the best overall mechanical properties.