EFFECTS OF Zr ON GRAIN BOUNDARY AND MECHANICAL PROPERTIES IN Ni_3Al ALLOYS
Zr对Ni3Al晶界及力学性能的影响

The yield and ultimate strengths increase with the amount of Zr increasing. If an additive of Zr less than 0.7 at.-%. the elongation of the alloy increases with Zr content growing. If Zr added up to 1.2 at-%. the effect of Zr improving ductility of the alloy is fall off. Auger study indicated that the amount of Zr segregated to the GB is about 3 times greater than that in the bulk. SEM investigation showed that the fracture mode changes from intergranular in Ni-24.0 Al and Ni-24.0 Al-1.2Zr (in at.-%) alloys to the mixed of interand trans-granular in Ni-24.0 Al-0.3 Zr and Ni-24.0 Al-0.7 Zr (in at.-%) alloys. These results manifested that the effect of Zr improving the ductility in Ni3Al has strong relationship with the segregation of Zr at GB.