Carbon nanotube–copper (CNT/Cu) composites have been successfully synthesized by means of a novel particles-compositing process followed by spark plasma sintering (SPS) technique. The thermal conductivity of the composites was measured by a laser flash technique and theoretical analyzed using an effective medium approach. The experimental results showed that the thermal conductivity unusually decreased after the incorporation of CNTs. Theoretical analyses revealed that the interfacial thermal resistance between the CNTs and the Cu matrix plays a crucial role in determining the thermal conductivity of bulk composites, and only small interfacial thermal resistance can induce a significant degradation in thermal conductivity for CNT/Cu composites. The influence of sintering condition on the thermal conductivity depended on the combined effects of multiple factors, i.e. porosity, CNTs distribution and CNT kinks or twists. The composites sintered at 600°C for 5 min under 50 MPa showed the maximum thermal conductivity. CNT/Cu composites are considered to be a promising material for thermal management applications.

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Nanosized MX precipitates in ultra-low-carbon ferritic/martensitic heat-resistant 9Cr-W-MoVNbTiN steels were characterized by transmission electron microscope (TEM) using carbon film replicas. The steels were prepared by vacuum induction melting followed by hot forging and rolling into plates. The plates were normalized at 1100°C for 1 hour, cooled in air, and tempered at 700°C for 1 hour. The results show that bimodal nanosized MX precipitates distribute densely and homogeneously in the matrix within martensitic lath after normalizing-and-tempering heat treatment. The larger nanosized MX precipitates with the size of 30 to 50 nm are rich in Nb, while the smaller ones with the size of about 10 nm contain less Nb but more V. Small addition of Ti causes an increase in the number of the larger nanosized MX precipitates. The total number density of the nanosized MX precipitates in the ultra-low-carbon ferritic/ martensitic steels is measured to be over 300/lm 2 , much higher than that in conventional ferritic/martensitic steels. Short-term creep test results show that the ultra-low-carbon ferritic/ martensitic steels with high dense nanosized MX precipitates have much higher creep rupture strength than conventional ASME-P92 steel. The strength degradation of the ultra-low-carbon ferritic/martensitic heat-resistant steels during creep is also discussed in this article.

Diamond/Cu-xCr composites were fabricated by pressure infiltration process. The thermal conductivities of diamond/Cu-xCr (x = 0.1, 0.5, 0.8) composites were above 650 W/mK, higher than that of diamond/Cu composites. The tensile strengths ranged from 186 to 225 MPa, and the bonding strengths ranged from 400 to 525 MPa. Influences of Cr element on the thermo-physical properties and interface structures were analyzed. The intermediate layer was confirmed as Cr 3 C 2 and the amount of Cr 3 C 2 increased with the increase of Cr concentration in Cu-xCr alloys. When the Cr concentration was up to 0.5 wt.%, the content of the Cr 3 C 2 layer was constant. As the thickness of the Cr 3 C 2 layer became larger, the composites showed a lower thermal conductivity but higher mechanical properties. The coefficients of thermal expansion (CTE) of diamond/Cu-xCr (x = 0.1, 0.5, 0.8) composites were in good agreement with the predictions of the Kerner' model.