Production and Characterization of High Porosity Ti-6Al-4V Foam by Space Holder Technique in Powder Metallurgy


Abstract: The present study was undertaken to investigate the production of a high porosity, biocompatible Ti-6Al-4V alloy by space holder technique using spherical carbamide particles, and to characterize the produced samples by compression tests and SEM images. The technique includes the following steps: mixing of 100-600 \mu m diameter spherical carbamide particles with irregular Ti-6Al-4V alloy powder of <78 \mu m size, compaction of the mixture of carbamide particles and Ti-6Al-4V powders by cold uniaxial die pressing, removal of carbamide by melting and dissociation, and sintering of the compact. Optimum compaction pressure, which preserves carbamide sphericity while providing the required packing of Ti alloy powders, was found to be 450 MPa. Ti-6Al-4V alloy foams of porosities between 60% and 75% with mean pore sizes of \sim 400 \mu m and mean sphericity values of 0.65 were successfully produced. Yield strength was observed to exponentially decrease with porosity, which is typical of cellular metals, reaching significantly low values at around 65% porosity, which was thought to be a result of pore coalescence.

Keywords: Foam, Carbamide, Porosity, Ti6Al4V alloy, Space holder, Compression testing

Full Text: PDF