Fabrication and SPS microstructures of Ti–45Al–8.5Nb–(W,B,Y) alloying powders

Ti–45Al–8.5Nb–(W,B,Y) alloying powders were fabricated by Ar gas atomization process, and then were consolidated by spark plasma sintering (SPS). Results showed that the phases in the powders are related with the particle size, but both exterior and interior structures of the powders are dendritic. There are two types of microsegregations in the alloying powders, designated as S-segregation and NT-segregation, and they become finer with decreasing particle size. A typical fully lamellar (FL) microstructure along with two types of microsegregations, such as β-segregation and α-segregation, is successfully formed at 1200 °C. However, FL microstructure becomes coarser at 1300 °C. Three kinds of alloys sintered with different particle sizes have FL microstructure after the treatment at 1200 °C/40 MPa for 10 min, but there are differences in their lamellar colony sizes and microsegregations. It is favorable to refining lamellar colony and homogenizing microstructure if holding time is extended.