Effects of B, Hf and Zr additions on the mechanical properties and the microstructures of $Ni_3$(Al,Fe) intermetallic compound were investigated by tensile test, impact test, SEM and SIMS analysis.
It has been found that the additions of B , Hf and Zr to $Ni_3$(Al,Fe) did not induce grain size refinement. The yield strength of $Ni_3$(Al,Fe) is showed about 320MPa. $Ni_3$(Al,Fe) added B, Hf, Zr showed an anomalous variation of yield stress with temperature : the yield stress increases with the increasing temperature by the Kear-Wilsdorf Mechanism.
In the tensile test, $Ni_3$(Al,Fe) alloy containing 0.05at.% B showed about 10% maximum elongation, and $Ni_3$(Al,Fe) alloy containing 0.10at.% Zr showed about 14% maximum elongation, and $Ni_3$(Al,Fe) alloy containing 0.10at.% Hf showed about 30% maximum elongationn at R.T..
The fracture mode of $Ni_3$(Al,Fe) alloy were mixed , but the addition of B, Hf and Zr to the $Ni_3$(Al,Fe) alloy were observed completely transgranular fracture mode.
The SIMS analysis showed that the beneficial effect of B, Hf and Zr segregation on grain boundary strength is in qualitative agreement with a theory of grain boundary cohesion.
