Experimental study on thermal expansion coefficient of light aluminum and magnesium alloys by comparing results of dilatometry and zero-force test

In this research, the thermal expansion coefficient of two light materials, A356 aluminum and AZ91 magnesium alloys, was calculated experimentally using dilatometric and zero-force tests. In the zero-force test, the temperature of the sample, in the specified range, without applying any mechanical forces, with a heating/cooling rate of 2 °C/s, was changed and the thermal strain-temperature curve was plotted. The mentioned cycle was repeated at the temperature rate of 10 °C/s and the strain difference with the results of the previous cycle was added to the thermal strain as a correction factor during the main test. The results showed that at the rate of 2 °C/s, the thermal strain-temperature curve was linear and the material behavior was nonlinear and as a hysteresis loop at 10 °C/s. The error of dilatometric test results for aluminum samples was 47.52% and for magnesium samples was 48.69% and the error percentage of the zero-force test at 2 °C/s for aluminum samples was 1.68%, where it was 4.73% for magnesium specimens.