Preparation Of Cu Nano-powder And Study Of Sps Sintering And High Pressure Torsion

Pure Cu nanopowder are prepared by the direct current arc plasma evaporation method. The optimal process conditions are under a current of 300 A, 1:1 ratio of hydrogen to argon, and total gas pressure of 0.07 MPa. The morphologies of the prepared Cu nanopowders are observed by X-ray diffraction, scanning electron microscope and transmission electron microscope. XRD results show that the prepared powders are high purity and contain CuO phase, which belongs to the face centered cubic structure;And TEM results show that most of the nano powder are uniform with a lot aggregates. The mean grain size of the nano powder is 25 nm. At the same time we find that the powders show Lattice expansion and the smaller of the grain size is serious of the lattice expansion.We study the performance and grain morphologies of Cu bulk sintered at different temperatures(400 ℃, 500 ℃, 600 ℃ and 700 ℃). The Cu bulk have a single face-centered cubic phase. SEM photos show that the particle size gradually increases. The hardness values of Cu bulk sintered at different temperatures are separately measured using a nanoindentation mechanical test machine and the Vickers hardness test. The tensile strength and elongation are determined by tensile tests. The strength mechanism of the Cu bulk is discussed according to the mechanism of deformation and fracture.The sintered bulks of 500 ℃ are disposed under high pressure torsion. XRD results show that after HPT the bulks are still FCC structure, and the grain size decreases obviously. The hardness and density increase gradually. The dislocation density and grain size are the two main factors influencing the hardness.