Influence of modification of aluminum alloys on their thermal expansion

The change in the dimensions of a component with the change in temperature is described by a quantity called thermal elongation. It is one of the basic properties of every material and it is necessary to take it into account when designing a specific component for a given application. Sometimes higher thermal elongation is considered a positive property, but in most applications, there is an effort to reduce the magnitude of thermal elongation with increasing temperature. Incorrect design can result in component failure or destruction. The following research includes the two most important aluminum sub-eutectic Al-Si alloys, namely AlSi7Mg0.3 and AlSi7Mg0.6 used in the automotive and aerospace industries. They were chosen due to their very good technological and mechanical properties. The silicon content in these alloys is 5-3% by weight. The alloys will be analyzed and their elongation curves will be measured in the temperature range -14 to 400 oC and the morphology of the structure. To further improve the structure, grains and thus the resulting properties, the modification of alloys with strontium or AlSr10, titanium inoculation with AlTi5B1 and, last but not least, heat treatment hardening and subsequently a combination of these individual treatments will be used. Again, a morphological analysis will be performed to determine the changes in the structure after individual treatments and to measure the dilatation of the treated alloys in a given temperature range and to measure the coefficient of thermal elongation. The achieved measured results will be compared to determine the appropriate treatment of alloys to reduce the overall coefficient of thermal elongation, or to reduce the coefficient of thermal elongation for a certain temperature range.