Influence of the temperature of the impact pressing in vacuum on the density, structure and properties of the powder copper

Abstract

Studying of the influence of the densification temperature of a copper powder at impact load in vacuum on the density, structure and mechanical properties of samples is carried out. Preliminary pressed briquettes from a powder with the relative density ~58 % desified in a range of temperatures from 25 to 1050 оС. Properties defined on cut out of cylindrical pressing rectangular bars. For comparison of mechanical properties similar bars have been made from the industrial plate-type copper. It has been established that at impact consolidation of powder preparations in weight 45 g with energy 8 кJ the density at level of 97% is reached at room temperature. Porosity of the samples pressed in a range of temperatures of 250-450 oC makes 1%, at 650-750 oC- 0,2% and almost dense samples can obtain at temperature of 850 oC. The maximum tensile strength 430 МPа is observed at the samples condensed at 450 oC, and it more than the strength of the usual copper equal 340 МPа. The structure of powder samples with the maximum strength the most fine-grained, and cross-section plastic deformation y these samples is equal 40%. The samples densified at 650 oC have the strength 305 МPа and lateral contraction y of 70%. The increase of the densification temperature to 1050 oC leads to the decrease of strength to 230 МPа and increase of the plasticity y to 74%. The greatest values of the hardness - 1360 МPа and the yield strength at compression - 550 МPа are observed on the samples pressed at the temperature of 250 and 450 oC accordingly. Full text download