✍ Scribed by L.F. He; Y.W. Bao; J.Y. Wang; M.S. Li; Y.C. Zhou
No coin nor oath required. For personal study only.
A Hf-Al-C composite composed of Hf 3 Al 3 C 5 , Hf 2 Al 4 C 5 and Hf 3 Al 4 C 6 has been successfully synthesized by a hot pressing method; its microstructure and mechanical and thermal properties were systematically characterized. Hf-Al-C composite conserves the high hardness and stiffness similar to HfC. Interestingly, the composite exhibits much higher strength and fracture toughness than HfC due to its fine and anisotropic grains. Diffusion-accommodated grain-boundary sliding of Hf-Al-C ceramics at high temperature is inhibited by glass-free grain boundaries and tight interlocking of grains at grain-edge triple junctions, resulting in high remaining stiffness up to 1600 °C. Dislocations on the basal planes of Hf-Al-C ceramics with a Burgers vector of 1 3 h1 1 2 0i can be activated at high temperature. Hf-Al-C composite shows higher coefficient of thermal expansion and specific heat capacity as well as lower thermal conductivity than HfC. The superior mechanical and thermal properties make Hf-Al-C compounds good high-temperature structural materials.
📜 SIMILAR VOLUMES
The microstructure and the tensile properties of an Al-8.9 wt.% Si-3.2 wt.% Cu-0.9 wt.% Fe-0.8% Zn alloy processed by spray forming was investigated. The alloy was gas atomized with argon and deposited onto a copper substrate. The microstructure was evaluated by optical microscopy (OM), scanning ele
New Zr-based bulk glassy alloys in Zr-Al-Co and Zr-Al-Co-Cu systems were developed. The largest supercooled liquid region is upto 64 K for the Zr 55 Al 20 Co 25 alloy and 80 K for the Zr 55 Al 20 Co 20 Cu 5 alloy, respectively. Glassy rods with a diameter of 3 mm for the Zr 55 Al 20 Co 25 alloy and