FATIGUE BEHAVIOR OF NI3AL(B) ALLOYS AT ROOM-TEMPERATURE

The high cycle fatigue behaviour of high boron polycrystalline Ni3Al a lloys is studied. A single phase Ni3Al alloy with a mole fraction of 0 .6% B and a Ni3Al alloy containing a mole fraction of 1.0% B with a sm all amount of the boride eutectic at the grain boundaries are selected for investigation. High cycle fatigue tests at room temperature with R (minimum stress/maximum stress) 0.1 are conducted in air and at 30 H z. The results show that the Ni3Al(0.6% B) alloy is better than the Ni 3Al(1.0% B) alloy in the fatigue resistance, although, the latter is m uch higher than the former in static strengths. The fatigue fracture s urfaces are observed by SEM.