Abstract
The age-hardening behaviour of a spinodally decomposed low-carat gold alloy was investigated by means of hardness test, X-ray diffraction (XRD), field emission scanning electron microscopic (FESEM) observations, and energy dispersive spectrometer (EDS). An apparent hardness increase occurred at the initial stage of the aging process without incubation periods. Then, after a plateau, the hardness increased to the maximum value, and finally, the softening by overaging occurred. The age-hardening of the specimen is characterized by the fast increasing rate in hardness and the apparent delay of softening. By aging the solution-treated specimen, the fcc α0 phase was transformed into the Ag-rich α1, Cu-rich α2, and Zn–Pd-rich β phases through the spinodal decomposition process and the metastable phase formation. The first hardening stage which occurred during the early stage of spinodal decomposition without an apparent structural change was thought to be due to the interaction of dislocation with solute-rich fluctuations. The second hardening stage after the plateau was caused by the formation of the fine block-like structure with high coherency induced by the spinodal decomposition, which corresponded to the phase transformation of the metastable Ag-rich \(\alpha '_1 \) phase into the stable Ag-rich α1 phase. The remarkably delayed softening was caused by the slow progress of coarsening and resultant chaining of the Ag-rich α1 precipitates in the Cu-rich α2 matrix due to the uniform fine scale of the structure.
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ADA (1972) Guide to dental materials and devices, 6th edn. American Dental Association, Chicago, p 183
Yasuda K, Ohta M (1982) J Dent Res 61:473
Ohta M, Shiraishi T, Yamane M, Yasuda K (1983) Dent Mater J 2:10
Nakagawa M, Yasuda K (1988) J Mater Sci 23:2975
Udoh K, Fujiyama H, Hisatsune K, Hasaka M, Yasuda K (1992) J Mater Sci 27:504
Kim HI, Jang MI, Jean BJ (1997) J Mater Sci Mater Med 8:333
Hamasaki K, Hisatsune K, Udoh K, Tanaka Y, Iijima Y, Takagi O (1998) J Mater Sci Mater Med 9:213
Kim HI, Park YH, Lee HK, Seol HJ, Shiraishi T, Hisatsune K (2003) Dent Mater J 22:10
Lee JH, Yi SJ, Seol HJ, Kwon YH, Lee JB, Kim HI (2006) J Alloys Compd 425:210
Pan LG, Wang JN (2007) J Mater Sci Mater Med 18:171
Cullity BD (1978) Elements of X-ray diffraction, 2nd edn. Addison-Wesley publishing Co, Inc, Massachusetts, p 506
Massalski TB (1990) Binary alloy phase diagrams, 2nd edn. ASM International, Materials Park, pp 12–13, 28–29, 358–362
Kim HI, Jang MI, Kim MS (1999) J Oral Rehabil 26:215
Tanaka Y, Udoh K, Hisatsune K, Yasuda K (1994) Philos Mag A 69:925
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Park, MG., Yu, CH., Seol, HJ. et al. Age-hardening behaviour of a spinodally decomposed low-carat gold alloy. J Mater Sci 43, 1539–1545 (2008). https://doi.org/10.1007/s10853-007-2348-5
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DOI: https://doi.org/10.1007/s10853-007-2348-5