Ni-20Cr-20Fe-5Nb alloy with or without

was manufactured by mechanical alloying process and consolidated by spark plasma sintering (SPS). The grain size of the alloy with

was smaller than that of alloy without

which results from the effect of

suppressing grain growth. The tensile strength at room temperature was increased by the addition of

but decreased abruptly at temperature above

. It seems to result from the change of deformation mechanism due to fine grain size, that is, grain boundary sliding is predominant at above

while internal dislocation movement is predominant at below

. After conventional heat treatment process of solution treatment and aging, a small amount of
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phase was formed in Ni-20Cr-20Fe-5Nb alloy while a large amount of
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was formed in Inconel 718 in the previous report. This is due to exhaustion of Nb content by the formation of NbC during consolidation.