Original paper(Vol.45 No.11 pp.1205)

Influence of alloy elements on mechanical properties of Ni-Cu-Al alloys

Mori Takanobu; Yanai Yoshimi; Kimura Kei

Abstract:To develop a material for single layer warm damper of superconducting generator, the influence of alloy elements such as Cu, Al, Ti, C and Zr on strength and toughness in precipitation hardening Ni-Cu-Al alloys was studied.
In Ni-11%Cu-4.3%Al type alloys, the combined addition of Ti and C decreases g' particle diameter and distance between particles. 0.2% proof stress of the alloys is increased by the combined addition of Ti and C.
In Ni-Cu-Al alloys, precipitation of g' at grain boundaries is promoted by increasing Cu, Al, Ti and C. g' at grain boundaries embrittles the alloys. In Ni-11%Cu-4.3%Al-0.4%Ti-0.15%C alloy, precipitation of g' at grain boundaries is suppressed by adding a small amount of Zr and toughness of the alloy is improved.
An adequate composition of Ni-Cu-Al alloy for single layer warm damper is approximately Ni-11%Cu-4.0%Al-0.3%Ti-0.13%C-0.03%Zr in terms of mechanical and electromagnetic properties.

Key Words:Ni-Cu-Al alloy, precipitation hardening, grain boundary reaction, toughness, superconducting generator