The strength of certain Ni-Al-Ta and Ni-Al-Hf alloys containing ν- and ν-phases

The temperature dependence of certain Ni-Al-Ta and Ni-Al-Hf superalloys are investigated. From this investigation it is hoped to determine the potentialities of good elevated temperature properties by a solution of tantalum and hafnium, based on the ν' phase. For this purpose five different tantalum- and hafnium-containing alloys are studied by changing the volume fractions of ν' and ν phases and the Ta and Hf content. The flow stresses of these alloys show two types of behaviour at low deformation temperature: 1. insensitivity of the flow stress with increasing temperature. 2. increasing flow stress with increasing temperature up to a certain temperature. The temperature dependence of the flow stress of the alloys is qualitatively analysed in terms of the 'mixture rule'. (author)