Intermediate Temperature Embrittlement and Its Restraint in Ni-Cu-Al Alloy Ingot
Takanobu MORI and Yoshimi YANAI
Abstract:Intermediate temperature embrittlement and its restraint were studied about Ni-Cu-Al alloy ingot for single layer warm damper of superconducting generator. Cracking of Ni-Cu-Al alloy ingot occurred when the ingot was given homogenization heat treatment. It is supposed that the cracking has close relationship to intermediate temperature embrittlement of the Ni-Cu-Al alloy ingot. It was found that increase of Cu, Al, Ti or C promotes the intermediate temperature embrittlement and reduces elongation at 625C in Ni-Cu-Al alloy ingot. However addition of Zr or B restrains the intermediate temperature embrittlement and increases elongation at 625C in Ni-Cu-Al alloy ingot. Electro-slag remelted ingot of Ni-12.2%Cu-4.15%Al-0.36%Ti-0.15%C alloy which is added 0.039%Zr weighed 21 tons and it was given homogenization heat treatment, however cracking of the ingot did not occur. Key Words:Intermediate temperature embrittlement, Cracking, Ni-Cu-Al alloy, Superconducting generator