Highlights
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It is clearly shown that SPS is a viable technique to fabricate highly reactive ceramic-metal systems with active components. 1233 K, 300 MPa, and 8 minutes are optimized processing conditions to produce fully-dense NiTi/Ti3SiC2 composites with maximum fractions of transformable NiTi, which are responsible for the high mechanical damping of the composites.
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The Ni and the “A” element diffusions, respectively, from NiTi and MAX phases initiate two-phase reactions. The NiTi-Ti3SiC2 reactions occurred at a lower rate than the NiTi-Ti2AlC reactions, so preserved transformable NiTi in the NiTi/Ti3SiC2 composites is more than that in the NiTi/Ti2AlC composites.
Abstract
Spark plasma sintering (SPS) was used as a fast consolidation technique to reduce reactions during powder consolidation of a highly reactive system (shape memory alloy/ternary carbide composites), which could not otherwise be fabricated using conventional methods. NiTi/Ti2AlC and NiTi/Ti3SiC2 powder mixtures, each with a 50/50 volume ratio, were processed in the 1233–1373 K temperature range under 100–300 MPa for 3–30 minutes. Phase transformation behavior of the composites was studied using differential scanning calorimetry and was compared with starting powders to evaluate the transformable NiTi in the composites. The effects of starting materials and processing conditions (sintering temperature, soaking time, and sintering pressure) on densification, reaction, and transformable NiTi were studied. A high-pressure (300 MPa) run at 1233 K for 8 minutes produced a fully-dense NiTi/Ti3SiC2 composite with a maximum percent of transformable NiTi. Based on phase analysis on the interfacial reaction layers, we developed the reaction mechanisms between NiTi and Ti3SiC2 or Ti2AlC during SPS. It is clearly shown that SPS is a viable technique to fabricate highly reactive ceramic-metal system with active components.
