Effect of pressure in pore on pore morphology of porous Cu-1.3Cr alloy with directional pores

Abstract

Cu-1.3Cr alloys with directional pore structure were fabricated under hydrogen atmosphere. The pore morphology during the solidification is investigated. It is found that the porosity is increased from 18% to 44% and the average pore diameter was decreased from 3.24 mm to 0.44 mm when the hydrogen pressure varies from 0.1 MPa to 0.6 MPa. Theoretical analysis shows the gas pore pressure drops significantly during the growth of pore. For a coarse pore, the drops of pore pressure will result in a backflow of the melt from solidification interface into gas pore, and this will result in a “bamboo” like structure. For small gas pores, the pressure difference between two neighboring gas pores drives the hydrogen gas from the short one to the long one. This is the reason that a short pore more easily coalesce with a long pore.

Keywords

• cu-cr alloy
• metal-hydrogen eutectic
• pore pressure
• pore morphology