Temperature dependence of thermal expansion coefficient for palladium-based binary alloy

Understanding how materials expand with temperature is vital in engineering and dental applications. Prior research has shown that thermal expansion coefficients vary with composition and phase changes. However, no prior work had resolved how these coefficients behave in palladium-based alloys during transformations. This gap motivated the current investigation into Pd-Ag, Pd-Cu, and Pd-Co systems. These alloys are commonly used in dental restorations, where thermal stability is crucial. Researchers needed to determine how the expansion changes with temperature and composition. The study aimed to clarify the relationship between thermal expansion and phase transformations. This knowledge would help improve the design of dental materials. The focus was on alloys without transformation in porcelain firing ranges.

The goal was to measure how thermal expansion coefficients change with temperature in palladium-based alloys. Specifically, the study examined Pd-Ag, Pd-Cu, and Pd-Co systems. Researchers wanted to understand the behavior of these alloys during porcelain firing. They aimed to determine if a linear equation could describe the expansion in stable temperature ranges. The study also sought to assess the impact of phase transformations on expansion. By measuring before and after transformations, the team could evaluate stress control in dental restorations. The motivation was to provide data for better material design. The results would help in selecting alloys with predictable expansion properties.

The researchers measured thermal expansion coefficients for three binary systems: Pd-Ag, Pd-Cu, and Pd-Co. They used a heating and cooling rate of 5 degrees Celsius per minute. The measurements were taken up to 900 degrees Celsius. For alloys without phase transformation, a linear equation was used to model the expansion. The equation constants were calculated as a function of the added element’s weight. In alloys with phase changes, the expansion was measured before and after transformation. The order-disorder transformation was studied in Pd-Cu. The magnetic transformation was analyzed in Pd-Co. The data was used to estimate expansion at any temperature and composition.

The thermal expansion coefficients of stable alloys were well described by a linear equation. The constants in the equation varied with the weight of the added element. For alloys without transformation, the model accurately predicted expansion at any temperature. The Pd-Cu alloy showed changes in expansion before and after order-disorder transformation. The Pd-Co alloy exhibited different expansion values before and after magnetic transformation. These differences suggest that phase changes affect thermal behavior. The results indicate that expansion can be controlled by selecting the right alloy. The study provides a method to estimate expansion for any composition and temperature.

The study shows that thermal expansion in stable palladium-based alloys can be modeled using a linear equation. The equation constants depend on the weight of the added element. The model allows for accurate estimation of expansion at any temperature and composition. The results suggest that phase transformations influence expansion behavior. In Pd-Cu, order-disorder transformation alters the coefficient. In Pd-Co, magnetic transformation affects the expansion. The findings imply that using transformation can help control stresses in dental restorations. The study provides a practical method for predicting expansion. The approach may help in selecting materials with desired thermal properties.