Abstract
In order to investigate behavior of abnormal expansion of the iron-copper compacts, we compared the dilatometric curves of the compacts of the iron and the copper powders mixture with those of compacts which mixed the copper powder to the iron-copper alloy-powder. The dilatometric curves were obtained under the sintering conditions, which heated up to 1423 K by the heating rate of 1.66×10-1 K/s, held for 3.6 ks at 1423 K and cooled down at a rate of 3.33×10-1 K/s to room temperature.
The dilatometric curves of the compacts showed the different expansion behavior at temperatures above the copper melting point in spite of same chemical composition. All of the compacts of former case showed large expansion, but all of the compacts in latter case showed large contraction. The microstructures of sintered compacts also showed the different progress in alloying of the copper into the iron powder. Namely we could observe the segregation at alloy part of copper into iron powder in case of the sintered-compacts, which mixed the copper powder to the iron powder, but could not observe the segregation in compacts which mixed the copper powder to the iron-copper alloy-powder. But the penetration of liquid copper into the interstices between solid particles was occurred at both cases. Therefore, the showing of the different dimensional changes in the compacts in spite of same chemical composition is due to the alloying of copper into iron than the penetration of liquid copper into the interstices between solid particles.
