Twice reverse shape memory effect in CuZnAl shape memory alloy

The variations of the shape memory effects in the Cu-13Zn-15Al(mole fraction, %) alloy upon successive heating (the rate of heating is 5 degreesC/min) have been studied by means of rho-T curve, shape memory effect measurement, optical metallographical observation and X-ray diffraction. The first abnormal reverse shape memory effect occurs when the tested alloy is heated to the temperature below 320 degreesC; when it is heated to the temperature between 320 degreesC and 450 degreesC, the forward shape memory effect occurs; in the two stages, the shape of the sample remains the same as that in the furnace when it is taken out from the furnace and air-cooled; when the tested alloy is heated to the temperature above 450 degreesC, the shape of the sample remains unchanged during heating, but the second reverse shape memory effect occurs after it is air-quenched.