Effect of Lanthanum on the Heat Capacity and Changes in Thermodynamic Functions of AlMg5.5Li2.1Zr0.15 Duralumin-Type Aluminum Alloy

Abstract

The specific heat of lanthanum-containing AlMg5.5Li2.1Zr0.15 duralumin-type aluminum alloy has been measured during cooling in the range 300–800 K. We have derived polynomials representing the cooling rates of the lanthanum-containing alloys and a reference. Based on the experimentally determined cooling rates of the alloys and reference and their weights, we have obtained cubic polynomials for the temperature dependence of the specific heat. Using integrals of the specific heat, we derived polynomials for the temperature dependences of enthalpy, entropy, and Gibbs energy changes. The results demonstrate that, with increasing temperature, the specific heat, enthalpy, and entropy of the alloys decrease, whereas their Gibbs energy decreases. The lanthanum content of the alloys has the opposite effect.