INFLUENCE OF BORON ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF RAPIDLY SOLIDIFIED Ni_3Al

By means of nonstoichiometry,rapid solidification and adequate boron addition,the tensile strength and bending resistance of Ni_3Al has been improved.When adding 0.52 to 1.37 at.-% B into Ni_3Al,which has the beneficial effect on the ductility.If boron addition is too high, there are coarse Ni_(23)B_6 particles and NiB_(12) phases found at the grain boundaries.Boron modification in Ni_3Al promotes the ordering in the region near grain boundaries.The grain boundary of boron free Ni_3Al is a large angle one,but turns into a small angle grain bound- ary with sub-grains of dislocation characteristics when the boron content in Ni_3Al reaches 1.37 at.-%.