The Preparation Of Cu-Al₂O₃Composite Bulk By Internal Oxidation Of Cu-Al Alloy Sheets

Dispersion strengthened copper alloy is a composite which fine dispersion particleis introduced in the Cu matrix as a strengthening phase. It has been a hot area ofresearch in the copper-based composites field, due to its high thermal conductivity andelectric conductivity, excellent high-temperature performances and good wear-resistingproperty. Internal oxidation technique is commonly used to prepare dispersionstrengthened copper alloys and can be divided into powder and sheet internal oxidationtechnologies. The former needs a large investment of equipment; the latter with simpleprocess and less equipment investment is currently only applied in the preparation ofdispersion strengthened copper alloy sheets. To our best knowledge, there are fewpapers reported on the production of bulk dispersion strengthened copper alloys usingsheet internal oxidation technology.In this paper, Cu-Al2O3bulk was obtained by using hot extrusion forming andsheet internal oxidation. The microstructure and properties of the Cu-Al2O3sheetsobtained respectively with different Al content under the same internal oxidating timeand the same Al content under different internal oxidating time are comparativelystudied. The Cu-Al2O3bulk was prepared after stacking, sealing and hot extrusion ofCu-Al2O3sheets. Subsequently the microstructure and properties of the Cu-Al2O3bulkare investigated.In internal oxidation layer, the grains of surface layer are obviously smaller thanthat of inside layer. In the same internal oxidation condition, internal oxidation depth ofthe composites decreased with increasing of Al content, while the microhardness at thesame depth increased. A great many of small γ-Al2O3particles with diameter of about20~50nm and particle spacing of50~150nm were diffusely distributed on Cu matrix.The two phases have a coherent relationship of (022)Cu//(220)γ.Cu-0.16%Al alloy sheets with the diameter of89.7mm and the thickness of0.5mm were internally oxidated at900℃for8h. And then they were cleaned, stacked, sealed and hot extruded at800℃，successfully getting the Cu-Al2O3bulk with adiameter of19.7mm. Cu-Al2O3rod (bulk) was drawn to a production required wirewith diameter of3mm. The cross sections of the hot extrusion rod and cold drawn wirepresent a ring structure. The electric conductivity of the rod is96.3%IACS. The wirewith an average electric conductivity of94.2%IACS have a yield strength of417MPaand a tensile strength of445MPa.