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To explore the mechanism of phase transformation, YTa 3 O 9 was prepared by an integrated one-step synthesis and sintering method at 1500 °C using Y 2 O 3 and Ta 2 O 5 powders as starting materials. High-temperature XRD patterns and Raman spectra showed that a phase transformation from orthorhombic to tetragonal took place in YTa 3 O 9 through the bond length and angle changes at 300–400 °C, which caused a thermal conductivity rise. To inhibit the phase transformation, a high-entropy (Y 0.2 La 0.2 Ce 0.2 Nd 0.2 Gd 0.2)Ta 3 O 9 (HE RETa 3 O 9) was designed and synthesized at 1550 °C using the integrated solid-state synthesis and sintering method. In tetragonal structured HE RETa 3 O 9 , phase transformation was inhibited by the high-entropy effect. Furthermore, HE RETa 3 O 9 exhibited low thermal conductivity, and its tendency to increase with temperature was alleviated (1.69 W/m·K, 1073 K). Good phase stability, low thermal conductivity and comparable fracture toughness to YSZ make HE RETa 3 O 9 promising as a new thermal barrier coating material. [ABSTRACT FROM AUTHOR]

In this paper, copper-graphite composites were prepared through powder metallurgy technique (hot press sintering) in order to figure out the impact of graphite by varying concentrations and mesh sizes. SEM and XRD were performed to analyze the microstructure and phase analysis. Hardness and thermal conductivity of the composites were measured to check the effect of graphite concentrations and varying mesh size on copper-graphite composites. At low concentration 3 wt% graphite, the hardness values were significantly increased and excellent result was obtained at 3500 μm mesh size (65 HV), while for copper the value was 40 H V. The best thermal conductivity horizontal to vertical ratio difference (2.71) was obtained at 5 wt% 3500 μm mesh size much higher than pure copper (0.93). • Cu-GF composites were successfully fabricated through powder metallurgy route. • Effect of mesh sizes and different concentration of GF is observed on Cu-GF composites. • The hardness of Cu-GF composites improve with the addition of GF. • The anisotropic TC ratio also improves with the addition of GF. [ABSTRACT FROM AUTHOR]

Here, the author fabricated copper-reduced graphene oxide composites by using conventional powder metallurgy technique by varying the amount of reduced graphene oxide. SEM and Raman analysis were used to characterize micro-morphology and disorder in the bulk composites. Tensile, thermal and microhardness testing were conducted to observe the behaviour of Cu-rGO composites. Interesting results were obtained after testing; the materials ultimate tensile strength, ductility, thermal conductivity and hardness were increased significantly compared to pure Cu. An increase in 31% ultimate tensile strength, ~200% ductility, 9.5% thermal conductivity and 90% hardness were noticed by using a very small amount of rGO 0.5 wt%. Laser irradiation test was also proved the good heat dissipation properties of Cu-rGO composites by increasing the amount of rGO. This extraordinary simultaneous increase in mechanical and thermal properties is remarkable and gave us a new way for the fabrication of higher strength-ductility and strength-conductivity based composites. • Cu-rGO composites were prepared by adopting conventional powder metallurgy. • The good interface bonding was observed in the composites. • The extraordinary increase in ultimate UTS, ductility, TC and hardness were observed. • Laser irradiation test proved the excellent heat transmittance of composites. [ABSTRACT FROM AUTHOR]

The good interface bonding is the basic requirement of metal-graphene composites to improve their mechanical properties. Here, we fabricated the hybrid composites through traditional powder metallurgy method. SEM and XRD were conducted to elaborate the microstructure and crystal orientation of powder as well as bulk composites. Tensile and hardness test was carried out to check the effect of graphene on copper-titanium carbide composite. Titanium carbide/copper-graphene (0.1 wt%) composite have excellent yield strength, ultimate strength and hardness higher than pure copper and also from copper-titanium carbide composite. The thermal conductivity values and anisotropic thermal conductivity ratio of titanium carbide/copper-graphene (0.1 wt%) composite are also far better than pure Cu. The results of mechanical and thermal properties demonstrate that these materials can be a better candidate to use in the thermal packaging system. • Cu–TiC and TiC/Cu-G composites were fabricated through powder metallurgy method. • The interface bonding between Cu–TiC and TiC/Cu-G(0.1) composites are really good. • The addition of G in Cu–TiC enhances the tensile and hardness properties. • The anisotropic TC ratio increased with the addition of graphene in Cu–TiC composite. [ABSTRACT FROM AUTHOR]

In this study, the effect of novel metal tantalum was investigated on the properties of copper-graphite composites. The complete mechanical behavior of copper-tantalum-graphite hybrid composites was examined. The addition of tantalum increased the compressive, tensile and bending strength of composites as well as the hardness and thermal conductivity. The compression, tensile, bending and hardness values for Cu–Ta-GF (0.5) composites are 20.7%, 138%, 69% and 93% higher than pure Cu and these are also far better than Cu-GF composites. The excellent mechanical and thermal properties with good relation of strength-ductility ratio open up a new window to use these materials as heat sinks in thermal packaging system. • The Cu-GF-Ta hybrid composites were fabricated successfully. • Effect of Tantalum metal was checked on Cu-GF composites. • Remarkable mechanical properties were noticed with the addition of Ta alloying element. • The interface bonding was almost improved significantly. [ABSTRACT FROM AUTHOR]