Change the YOUNG’s modulus

I'm running this coupled heat transfer-structural model .The analysis is time dependent. In my model ,as the temperature rising, the metal has deformed (such as swelled).But in reality,the metal could be melting , so the elements could not taked into account(death elements) .So when the temperature is reaching the melting point, I want to apply a very low YOUNG’s modulus E as a subdomain setting.For the exemplary process flow a YOUNG’s modulus of 10exp(12) Pa was used.This low YOUNG’s modulus ensures that death elements do not influence the bending stiffness of the underneath .But I don't know how to change the YOUNG’s modulus.

Could someone can help me solve this problem?In short，when temperature reaching the melting point, apply a very low YOUNG’s modulus E as a subdomain setting.