Non-linear ultrasonic testing of the long-period stacking ordered phase volume fraction in magnesium alloys

The content of the long-period stacking ordered (LPSO) structure strengthening phase has an important influence on the tensile strength, compressive strength, ductility and other mechanical properties of magnesium (Mg) alloys. Therefore, effective detection of the volume fraction of the LPSO phase plays an important role in understanding the properties of the alloy. Focused on the problem that the accuracy of the non-destructive testing method for the LPSO phase precipitates with micron or nanometer scale is not sufficient, this paper studies the non-linear ultrasonic testing of the Mg alloy LPSO phase volume fraction. Based on the non-linear ultrasonic testing theory, the non-linear ultrasonic simulation of the simulation models with different LPSO phase contents was carried out using finite element simulation. The relationship between the volume fraction of the LPSO phase and the non-linear coefficient of ultrasonic simulation was studied and a non-linear ultrasonic testing system was established to test the Mg alloy specimens with different LPSO phase volume fractions. The results show that the non-linear ultrasonic testing method is sensitive to changes in the LPSO phase volume fraction. Thus, this method is an effective way to detect the LPSO phase volume fraction.