抄録
Powder Injection Molding (PIM) of Ti-48Al was attempted with a special interest in its densification behavior at different processing conditions such as debinding atmosphere, sintering temperature and time. Specimens debinded in H2 showed high densification rate, resulting in 97% density after sintering at 1350°C in vacuum for 3 hours. Fine Al2O3 particles about 1 μm size were observed along the prior particle boundaries of the sintered specimens. Specimens debinded in Ar and sintered in vacuum at 1350°C and 1400°C for 3 hours resulted in similar densifications of 91.7% and 91.5%, respectively. The microstructures were, however, quite different; Sintering above α/(α+γ) transus temperature showed a fully lamellar microstructure with a coarse grain size, whereas sintering at 1350°C showed a fine grained duplex microstructure. Presintering at 1000°C for 3 hours eliminated the macro pores and improved densification to 93.4% when the specimen was subsequently sintered at 1350°C for 3 hours. Densification was improved as the sintering time increased, reaching a near full density of 98.8% after 30 hours sintering at 1350°C.
