The Mechanical Properties of Precipitation Hardened Nickel Aluminum Alloys

Abstract

<p> The macroscopic mechanical behaviour of alloys is intimately related to their structure at the atomic level. The influence of small (<0.1μ) ordered coherent particles (𝛄') on the mechanical properties of Ni-Al alloys has been studied. The maximum strength of polycrystals occurs at 0.45 volume fraction 𝛄' and grain boundary embrittlement occurs at higher volume fractions. It was shown that long range order in the particles affects strength by increasing the anti-phase boundary energy. In monocrystals the deformation behaviour is strongly influenced by the amount of particles present. </p> <p> By growing very large particles of 𝛄' (~1.0μ) dislocation-particle interactions have been studied. Stacking faults have been observed in the particles whose bounding dislocation Burgers vectors were determined. By suitable heat treatment still larger 𝛄' particles (~10µ) were formed which had incoherent interfaces. The dislocation networks at the interfaces were analysed. </p>