Acoustic emissions of the composite are analyzed (24) to generate a signature of the stress relaxation events over time.

The combination of nickel and tin increase resistance of the alloy to elevated temperature stress relaxation.

When compared to other copper base alloys that include iron, zinc and phosphorus, the disclosed alloy has improved resistance to stress relaxation.

In stress relaxation, an instantaneous strain is applied to the sample and held constant.

A digital controller (12) controls the temperature and terminates thermal conditioning when the rate of stress relaxation decreases below the maximum rate which has been recorded (20).