Short-range ordering and mechanical properties of a Ni-20% Cr alloy

The mechanical behavior of a coarse-grained (100 mu m) nickel-base alloy nichrome (Ni-20%Cr) was studied in compression at temperatures ranging from 150 to 1000 degrees C. It was shown that in the temperature interval of 300-600 degrees C this alloy demonstrates the following features of mechanical behavior: i) positive temperature dependence of yield stress; ii) jerky flow associated with the Portevin-Le Chatelier (PLC) effect; 3) very high value (115 MPa) of "threshold" stress at 650 degrees C. These features of mechanical behavior can be related to short-range ordering (SRO). It was shown by differential scanning calorimetry that SRO takes place in this temperature range, causing PLC effect and positive temperature dependence of yield stress. In addition, SRO has persistency effect on yield stress and creep resistance.