Self-healing materials have recently drawn the attention of industry as a new solution to the degradation of materials. Recent progress on the field of autonomous self-healing metals has been in the line of self-healing creep-resistant steels. This is challenging due to the nanometer scale of the creep cavities and the fact that only 3D partially filled cavities can be examined to understand the phenomenon. As a consequence, valuable information is hard and expensive to acquire. This thesis proposes to study the surface precipitation phenomenon as an easier alternative to understand creep-cavity precipitation. Surface precipitation have only been studied in binary steels, therefore, the thesis focuses on the influence of the addition of a second self-healing element by studying the time evolution of gold tungsten containing iron based steels. The results provide new insights into the theory of self-healing steels, where tungsten has been found to decelerate the gold precipitation kinetics.