Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

Materials Research

Hyung-il Kim¹  Tae-wan Kim¹  Young-oh Kim¹  Su-yeon Cho¹  Gwang-young Lee¹  Yong Hoon Kwon¹  Hyo-joung Seol¹ 

[1] ,Pusan National University School of Dentistry and Medical Research Institute Department of Dental Materials,South Korea

关键词: spinodal decomposition;    metastable phase;    age-hardening;    lamellar-forming grain boundary reaction;   

DOI  :  10.1590/S1516-14392012005000169

来源: SciELO

【 摘 要 】

The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

【 授权许可】

CC BY   
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