In Situ Synthesis of Heat Resistant Gradient Composite on Steel Surface

A heat resistant gradient composite was synthesized in situ on steel with the self-propagating high temperature synthesis (SHS) reaction of 3Ni-Al-Ti-C system during casting. The phases, microstructure, and composition of the composite were analyzed by using an X-ray diffractometer (XRD), and a scanning electron microscope (SEM) coupled with an energy-dispersive X-ray spectroscope (EDS). The formation mechanism of the composite is also discussed. TiC/Ni3 Al/steel gradient composite is achieved by forming the gradient distributions of Fe, Ni, and Al, accompanied with the gradient variation of the microstructure from TiC/Ni3 Al, to TiC/Ni3 Al/steel, and to steel. The composite is in situ synthesized through whole reaction of 3Ni-Al-Ti-C system in liquid steel and densification procedure, and the liquid steel infiltrates into pores in the SHS product and forces liquid Ni3Al to form self-compaction further.