Synthesis and properties of nanocrystalline nonferrous metals prepared by flow-levitation-molding method
(1. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China; 2. Institute of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China )
Abstract: Nanocrystalline nonferrous metals (Cu, Al, and Ag) were synthesized by flow-levitation-molding method. The microstructure of the as-prepared nanocrystalline metals was characterized by XRD and FESEM. The microhardness and electrical resistivity were tested by the HMV−2 type Microhardness Tester and 6157 type Electrometer, respectively. The synthesis process was also studied. The results show that the spheriform particles in nanocrystalline metals have average grain size of 20−30 nm. The relative density of nanocrystalline Cu, Al, and Ag are 95.1%, 98.1% and 98.3%, respectively. The microhardness of nanocrystalline Cu, Al and Ag are 2.01, 2.11 and 1.26 GPa respectively, which are larger than those of their coarse-grained counterparts by the factor of 4.5, 14, and 2.5, respectively. The electrical resistivity of nanocrytalline Cu at room temperature is 1.5×10−7 Ω·m, which is higher than coarse-grained Cu by a factor of 7.5. The pressure is the predominant factor influencing the density of the as-prepared nanocrystalline nonferrous metals.
Key words: nanocrystalline; nonferrous metals; flow-levitation-molding; density; microhardness; electrical resistivity