Field-activated sintering of blended elemental γ-TiAl powder compacts: Porosity analysis and growth kinetics of Al3Ti

Various powder compacts with targeted compositions of TiAl and Ti3Al were consolidated by field-activated sintering, specifically spark plasma sintering (SPS) at various temperatures, to examine phase growth under a superimposed electric field. While compacts with a composition of TiAl showed significant porosity after sintering, Ti3Al compacts showed no porosity. The porosity is attributed principally to volume changes associated with the formation of Al3Ti and the Kirkendall effect. The kinetics underlying Al3Ti growth during SPS are also explained.