EFFECT OF MICROSTRUCTURE ON MECHANICAL PROPERTIES OF INCOLOY 907

Effect of microstructure on the mechanical properties of a precipitation strengtheningFe-Ni-Co based low expansion alloy,Incoloy 907.has been investigated under different heattreatments.The dispersed γ-phase is found to be the principal strengthening phase in thealloy.The microstructure of the alloy with even dispersed fine γ′-phase seems to have the bestmechanical properties.However,it will be worsened if the alloy was aged at some higher tem-perature or overaged to precipitate needle-like ε-phase.