*Article* **Scanning Rate Extension of Conventional DSCs through Indirect Measurements**

#### **Hannes Fröck 1, Michael Reich 1,\*, Benjamin Milkereit 1,2 and Olaf Kessler 1,2**


Received: 8 March 2019; Accepted: 28 March 2019; Published: 2 April 2019

**Abstract:** In this work, a method is presented which allows the determination of calorimetric information, and thus, information about the precipitation and dissolution behavior of aluminum alloys during heating rates that could not be previously measured. Differential scanning calorimetry (DSC) is an established method for in-situ recording of dissolution and precipitation reactions in various aluminum alloys. Diverse types of DSC devices are suitable for different ranges of scanning rates. A combination of the various available commercial devices enables heating and cooling rates from 10−<sup>4</sup> to 5 Ks−<sup>1</sup> to be covered. However, in some manufacturing steps of aluminum alloys, heating rates up to several 100 Ks−<sup>1</sup> are important. Currently, conventional DSC cannot achieve these high heating rates and they are still too slow for the chip-sensor based fast scanning calorimetry. In order to fill the gap, an indirect measurement method has been developed, which allows the determination of qualitative information, regarding the precipitation state, at various points of any heat treatment. Different rapid heat treatments were carried out on samples of an alloy EN AW-6082 in a quenching dilatometer and terminated at defined temperatures. Subsequent reheating of the samples in the DSC enables analysis of the precipitation state of the heat-treated samples. This method allows for previously un-measurable heat treatments to ge<sup>t</sup> information about the occurring precipitation and dissolution reactions during short-term heat treatments.

**Keywords:** EN AW-6082; AlMgSi alloy; differential scanning calorimetry; fast scanning; scanning rate extension; indirect measurements; dissolution; precipitation; time-temperature-dissolution diagram
