Can i use other materials like SS-316, Al instead of 4140 as target material for eddy current probes. What will be the effect on performance of probes by using different material?
It can be done but you will have to run a new calibration curve with the new material. With stainless it will change the scale factor (slope of the curve) and it will shorten the linear range.
Probably better to buy a probe and proximitor system that is calibrated for your material.