Self Healing of Creep Damage by Gold Precipitation in Iron Alloys1. Issue 5 (15th January 2015)

• Record Type: Journal Article
• Authors: Zhang, Shasha; Kwakernaak, Cees; Sloof, Willem; Brück, Ekkes; van der Zwaag, Sybrand; van Dijk, Niels
• Is Part Of: Advanced engineering materials. Volume 17:Issue 5(2015:May)
• Page Start: 598
• Page End: 603
• Publication Date: 2015-01-15
• Subjects: Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201400511
• Languages: English
• ISSNs: 1438-1656

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="adem201400511-sec-0001" sec-type="section"> <p>In the present study we demonstrate that autonomous repair of high‐temperature creep damage can be achieved in iron by alloying with a small amount of gold. Adopting a heat treatment that provides mobile gold within the iron matrix is found to significantly extend the creep lifetime at a temperature of 550 °C. Combined electron‐microscopy techniques demonstrate that the improved creep properties originate from selective precipitation of gold atoms within early‐stage creep cavities, before they can merge into micro‐cracks along the grain boundaries. The selective precipitation of gold atoms at the free surface of a creep cavity results in pore filling, and as a result autonomous repair of the creep damage. Grain boundaries and dislocations act as fast routes for solute gold transport from the matrix to the creep damage. Pore filling preferentially takes place at the highest loaded grain boundaries oriented perpendicular to the applied load. The efficiency to heal creep damage is found to depend strongly on the applied stress. For lower stress levels filling fractions of up to 80% of the open‐volume creep damage have been observed.</p> </sec> </abstract>