Microstructure characterization and mechanical properties of in situ synthesized Ti2(Al,Si)C reinforced Al composites

Abstract

A novel composite with in situ synthesized of Ti 2 (Al,Si)C solid solution reinforced Al matrix was fabricated in Ti 2 AlC-Al-Si material system via one-step solid solution and densification by spark plasma sintering method. The relationship between microstructure, phase composition and mechanical properties of composites doped with different Si content (1, 2 and 3 wt%) and fabricated at different sintering temperature (580, 570 and 560 °C) were investigated. The optimal sintering temperature of composites with increasing the Si addition was carefully determined. The interface reaction was effectively regulated under different Si additions. X-ray photoelectron spectroscopy ( XPS) and nanoindentation test results reveal that Si formed Si C covalent bond in Ti 2 (Al,Si)C solid solution, and with the increase of Si addition, the hardness and elastic modulus of Ti 2 (Al,Si)C increased by 6.75% and 4.23% in the composites prepared by the three optimal processes. The tensile tests show that when the addition of Si was 2 wt% and the sintering temperature was 570 °C, the composites demonstrated an optimal balance of strength and plasticity. The ultimate tensile strength reached 226 MPa with a strain of 14.33%. Moreover, when added to 3 wt% and the sintering temperature decreased to 560 °C, the composite achieved a significant improvement in elongation. The performance are mainly attributed to the strengthening of Ti 2 (Al,Si)C solid solution and the regulation of interface reaction. • In situ synthesized Ti 2 (Al,Si)C solid solution reinforced Al composite is fabricated by spark plasma sintering method. • The reaction phase TiAl 3 is inhibited by the increase of Si addition and decrease of sintering temperature. • With the increase of Si addition, the hardness and elastic modulus of Ti 2 (Al,Si)C increase by 6.75% and 4.23%. • The Al composite with 20 vol% Ti 2 AlC and 3 wt% Si demonstrates a large strain of 16.33%.