Enhanced mechanical properties of spark plasma sintered NiTi composites reinforced with carbon nanotubes

• Published in: Journal of alloys and compounds Vol. 617; pp. 505 - 510
• Main Authors: Lee, Junho, Hwang, Jaewon, Lee, Dongju, Ryu, Ho Jin, Hong, Soon Hyung
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25.12.2014; Elsevier
• Subjects: Applied sciences; Dispersion hardening metals; Elasticity. Plasticity; Exact sciences and technology; Mechanical properties; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metal matrix composites; Metals. Metallurgy; Powder metallurgy. Composite materials; Production techniques; Shape memory; Sintering; Mechanical properties; Metal matrix composites; Sintering; Shape memory; Titanium alloy; Elastic modulus; Ultimate strength method; Ball mill; Metal matrix composite; Strain energy; Carbon nanotubes; Composite material; Dispersion strengthened metal; Tensile strength; Spark plasma sintering; Transition metal alloy; Shape memory effect; Thermal hysteresis; Yield strength; Nanocomposite; Nickel alloy; Strength
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.08.091

•A NiTi composite reinforced by CNTs was prepared by powder metallurgical process.•Although TiC was formed by reaction of CNT and Ti, unreacted CNTs could be found.•CNTs had little influence on the shape memory effect of NiTi matrix.•Mechanical properties of NiTi were enhanced by unreacted CNTs. To enhance the mechanical strength of NiTi, 0.5vol% CNT/NiTi composite was fabricated by high-energy ball milling followed by spark plasma sintering. NiTi and 1vol% TiC/NiTi composites were also fabricated using the same process for comparison. Unreacted CNTs were observed in the CNT/NiTi composites, although some CNTs had reacted with Ti to form a TiC phase. Thermal hysteresis increased with the addition of CNTs due to increased frictional resistance to interfacial motion between CNT and NiTi matrix, and relaxation of the elastic strain energy in the NiTi matrix. The addition of CNTs, however, had little influence on the shape memory effect of NiTi. The elastic modulus, yield strength and ultimate tensile strength of the 0.5vol% CNT/NiTi composite were greater than that of the NiTi. This improvement was attributed to the effective load transfer to the unreacted CNTs.