Fabrication And Performance Of Co-continuous TiC_x/Nickel-base Alloy

Ni base alloy performs excellent in holding high temperature, stable microstructure and properties, less predictable damage, antioxidant capacity etc., meanwhile, TiCx enjoys high hardness, high melting points, resistant abrasion and perfect wettability etc. Therefore, fabricating composites processing merits of Ni base alloy and TiCx has fundamental meanings. This thesis analyzes the technology of fabricating co-continuous structure TiCx/Ni matrix composites based on Ti3AlC2 through non-pressure infiltration of porous ceramics as precursor. Also, the technology of fabricating prefabricated part of porous ceramics, non-pressure infiltration, the reaction mechanism, structure and mechanical properties of composites etc. are equally analyzed.The experimental results show:1. Successfully fabricate porous Ti3AIC2 ceramic skeletons with adjustable open porosity by means of non-pressure sintering using Ti powder, Al powder, Sn powder and TiC powder, and water-washing NaCl. In the former scenario, condition is controlled under 1380℃ so as to achieve apparent porosity of 54.3%±3%, while the latter one makes flexible apparent porosity of 20%-50%.2. Through analyzing reaction mechanism of Ti3AlC2’s dissolution triggered by melting Ni base alloy under high temperature, and it turns out Al atom is able to be dissolved from Ti3AlC2, and with further reaction with Ni base alloy, phases like Ni3 (Al, Sn, Ti)、Cr3Ni2Si、CrB etc. are generated, all of which contributes to a ceramic skeleton composed of TiCx particles and three-dimensional network structure filled with Ni base alloy.3. Non-pressure infiltration helps achieve TiCx/Ni matrix composites with high density and big volume. The possibility of shrinkage grows along with the rising infiltration temperature under sintering, thus making the density and relative density of TiCx/Ni matrix composites lower. It shows that when the temperature climbs from 1150℃ to 1250℃, the density falls from 6.89g/cm3 to 6.75g/cm3, and the relative density declines from 98.64% to 96.64%.4. The bending strength and compressive strength of TiCx/Ni matrix composites are improved along with the rising infiltration temperature, thus resulting in more dispersing numbers. Set parameters as 1250℃ and holding 90 min, both the bending strength and compressive strength reach the highest, indicating the bending strength of 930.6MPa±160.2MPa, the compressive strength of 2.85GPa±0.13GPa, the yield strength of 1.87GPa±0.15GPa, and the fracture strain of 11.69%±1.85%.5. Along with the rising infiltration temperature, the fracture toughness denoted by KIc grows from 13.70±0.69MPa·m1/2 to 16.86±1.26MPa~m1/2, indicating that TiCx/Ni matrix composites performs well in preventing crack propagation.6. The Vickers hardness of TiCx/Ni matrix composites declines in pace with the growth of test load, however, if the margin of decline reduces, relevant standard deviation falls as well. As has demonstrated, when the test load is set as 300N, the hardness of materials reaches the highest under 1250℃ and holding 90 min, saying 7.42GPa±0.16GPa.