The effect of TiC addition on the mechanical properties and thermal expansion coefficient during laser metal deposition of invar 36 alloy

Invar 36 alloy is a binary Fe-Ni alloy characterized by an extremely low coefficient of thermal expansion, which wasfound extensive application in emerging industrial fields. Laser metal deposition, as an innovative additive manufacturing technique, is extensively utilized for the fabrication of alloy materials, and possesses distinctive advantages in the preparation of Invar alloy. However, the mechanical strength of the as-prepared Invar alloy is typically quite low. In this work, to enhance the strength of Invar alloy, TiC ceramic particles were incorporated during the laser deposition process. The effects of TiC content on microstructure, phase composition, mechanical properties and thermal expansion coefficient of Invar 36 alloy deposited via laser waswere systematically investigated. The results demonstrated a significant refinement of the grain structure upon the incorporation of TiC ceramics. When the mass fraction of the ceramic particles in the mixed powders was optimized between 0.8 % and 2 %, the tensile strength of the specimen exhibiting the best performance peaked at 560 MPa, with a maximum elongation of 35 %. Additionally, the specimens with added ceramic particles, consistently displayed a lower coefficient of thermal expansion.