File:Thermal expansion of aluminum and various important aluminum alloys (IA scientificpapers49719geor).pdf

This paper gives data on the linear thermal expansion of 4 samples of aluminum and 51 samples of important aluminum alloys. The preparation, chemical composition, heat treatment, etc., are included. Most of the specimens were examined from room temperature to about 500 degrees C. Typical expansion curves of the various groups of samples are shown and discussed. A description of the apparatus used in this research and a review of available information obtained by previous observers on the thermal expansion of aluminum and some of its alloys are given. The expansion of cast aluminum (99.5 percent) from room temperature to 610 degrees C. is represented by the following equation: Lt==Lo[I+(22.58 t+0.00989 t2)10(-6)] The relations between the chemical compositions and coefficients of expansion of aluminum-copper alloys (4 to 12 percent copper) and aluminum-silicon alloys (4 to 12.5 percent silicon), are shown in figures. The anomalous expansion of two aluminum-zinc alloys at constant temperature (about 270-degrees C. on heating) is shown. From the results of previous observers and the present research, it is evident that the aluminum-zinc alloy of eutectoid composition (about 79 percent zinc) shows the greatest change in expansion at the transformation or eutectoid temperature. A triangular diagram is shown which indicates the effect of change of composition on the coefficients of expansion of aluminum-silicon-copper alloys lying near the aluminum corner of the ternary system. The table in the summary gives a comparison of the average coefficients of expansion of the various groups of samples investigated.