Effects of TiC-TiB2 Nanoparticles on Microstructure and Mechanical Properties of As-cast Graphite Ductile Irons

Author of the article:WANG Bingxu1 , HU Zirui1 , QIU Feng2 , HU Ming1 , CUI Weiwei1 , YANG Jinlin1 , ZHANG Yu1

Author's Workplace：1. School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China; 2. School of Materials Science and Engineering, Jilin University, Changchun 130022, China

Key Words：TiC-TiB2 nanoparticles; graphite ductile iron; as-cast microstructure; mechanical properties; refining mechanisms

Abstract：A new type of ductile cast iron was prepared by aluminum base master alloy containing prefabricated endogenous nano-TiC-TiB2 particles. The effect of dual-phase nano-particles on the as-cast microstructure and mechanical properties of ductile cast iron was studied. The results show that with the addition of nanoparticles, the spheroidization rate of graphite spheres in the as-cast microstructure increases by 15.9%, the average diameter decreases by 35.8%, and the number of graphite spheres per unit area increases by 66.3%. In the matrix, the content of ferrite increases, and the lamellar structure of pearlite is obviously refined. In the test of mechanical properties, the hardness of ductile cast iron reinforced by nanoparticles has no obvious change. The yield strength, tensile strength, elongation and impact toughness of ductile cast iron are increased by 5.2%, 3%, 32.1% and 50.4%, respectively. In the fracture morphology analysis, it is found that the addition of nanoparticles could promote the plastic deformation, the cleavage plane with river pattern disappeared, and a large number of tearing edges and tiny dimples appeared around the graphite spheres. The fracture mechanism change from brittle fracture to ductile fracture.