Abstract
Abstract Mechanical properties of metallic alloys typically are adjusted by heat treatments utilizing controlled microstructural changes, i.e., solid-solid phase transformations. These include non-diffusional martensitic transformation, diffusional secondary-phase precipitation, and/or dissolution. Proper technical application of these heat treatments requires knowledge about the characteristic temperatures and times but moreover about the time dependence (kinetics) of the active phase transformation. All relevant solid-solid phase transformations show a heat effect (for instance, precipitation = exothermic; dissolution = endothermic). Therefore, one outstanding measurement technique to analyze these phase transformations is calorimetry, particularly differential scanning calorimetry (DSC). Combinations of different DSC methods and devices nowadays allow to cover 10 orders of magnitude in heating and cooling rates (10 − 5 –10 5 K/s). Besides, the relevant solid-solid phase transformations often cause a change in sample volume/length, which can be analyzed by dilatometry. Appropriate sophisticated measurement setups and methods will be briefly reviewed. The most recent developments are discussed in detail, using dissolution and precipitation reactions in aluminum alloys as examples. Basically, these techniques enable the recording of time-temperature transformation (or precipitation and dissolution) diagrams for diverse metallic alloys during heating, isothermal annealing, and even during continuous cooling, making DSC and dilatometry very mighty techniques for the analysis of solid-solid phase transformations.
Published Version
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