硼分布对Ni_3Al晶界的影响

EFFECT OF BORON DISTRIBUTION ON GRAIN BOUNDARIES OF NI_3Al

用径迹显微照相技术(PTA)和TEM研究了含0.065wt％B的Ni_3Al合金中的硼分布对其晶界的影响。研究表明,当该合金于700、850、1000℃保温并空冷时,存在硼的晶界偏聚,且偏聚量随着保温温度的升高而减少,保温温度为1000℃时,偏聚量很少;保温温度为700℃或850℃时,偏聚量较大。硼晶界偏聚对该合金晶界内聚力的提高起着关键作用,硼的偏聚量较大时,合金呈完全穿晶断裂;硼的偏聚量较少时,合金呈完全沿晶断裂。

The effect of boron distribution on grain boundaries in Ni_3Al alloy containing 0.065％ B by weight is studied by means of Path Tracing Analysis(PTA)and TEM.It is found that when the hold- ing temperature is kept at 700,850 and 1,000℃ and air cooled,there is boron segregated at grain boundaries.The amount of boron segregated decreases with the holding temperature.More boron segre- gates at 700 and 850℃ and very little does at 1,000℃.The boundary segregation of boron is a deci- sive factor for increasing the cohesive power inside the grain boundary:full transcrystalline fracture occurs when the amount of boron segregated is high and full fracture along the grain boundary occurs when the amount of boron segregated is low.