EFFECT OF 4TH ELEMENTS ON DAMPING CAPACITY OF MN-20CU-5NI ALLOY

An attempt has been made to develop manganese-based and workable damping alloys containing 20 at% copper and 5 at% nickel, together with 2 or 5 at% additive elements, such as iron, aluminum, chromium, cobalt, and vanadium. Furnace cooling was effective for increasing the damping characteristics in most alloys tested. Aging treatment at 698 K after annealing showed a minor increase in damping characteristics as compared with cooling rate. The alloy, Mn-20Cu-5Ni-2Fe, showed a value of 0.32 in logarithmic decrement (a value of 47% on specific damping capacity) after furnace cooling from the annealing temperature of 1173 K. The decrement in this alloy was superior to that of the Mn-20Cu-5Ni alloy reported in the previous paper. In Mn-20Cu-5Ni-2Fe-2Al and Mn-20Cu-5Ni-2Fe-5Al alloys an equivalent decrement was obtained. It was deemed necessary for improvement of the damping capacity to add elements which have large solubility with regard to manganese and copper without precipitation or primary crystallization.