Effects of Heat Treatments on Mechanical Strength of laser-welded Equi-atomic AuCu-6at%Ga Alloy

Abstract

There is little information available on the mechanical strengthening of laser-welded gold alloys to achieve reliable dental prostheses. This study examined the hypothesis that heat treatments increase the mechanical strength of a laser-welded equi-atomic AuCu-6at%Ga alloy with age "hardenability" at intra-oral temperature. Cut cast gold alloy plates were laser-welded. The specimens were given one of three heat treatments: (1) solution treatment, (2) high-temperature aging after solution treatment, and (3) simulated intra-oral aging after solution treatment. As-cast and uncut specimens were also prepared. Tensile testing was conducted, and the breaking stress and yield strength were recorded. The yield strength values of all the heat-treated specimens nearly reached the values of the corresponding heat-treated control specimens. The results of this study indicated that, for high mechanical strength to be achieved, the laser-welded alloy tested should be aged at a high temperature or be intraorally aged after being laser-welded.

Keywords

gold alloy laser welding joint strength penetration depth.

Get full access to this article

View all access options for this article.

References

Asaoka K. , Tsuji K. , Kuwayama N. (1984). Correlation between microstructure of Ag-Pd-Au-Cu alloy and changes in shape. J Biomed Mater Res 18:707-716.

Berg E. , Wagner WC , Davik G. , Dootz ER (1995). Mechanical properties of laser-welded cast and wrought titanium. J Prosthet Dent 74:250-257.

Chai T. , Chou CK ( 1998). Mechanical properties of laser-welded cast titanium joints under different conditions. J Prosthet Dent 79 :477-483.

Herø H. , Jorgensen R. , Sorbroden E. (1982). A low-gold dental alloy: structure and segregations , J Dent Res 61:1292-1298.

Leinfelder KF , O'Brien WJ , Taylor DF (1972). Hardening of dental gold-copper alloys. J Dent Res 51:900-905.

Nakagawa M. , Matsuya S. , Ohta M. ( 1992). Effect of microstructure on the corrosion behavior of dental gold alloys. J Mater Sci Mater Med 3:114-118.

Ohta M. , Shiraishi T. , Nakagawa M. , Matsuya S. (1994). Dental gold alloys with age-hardenability at intraoral temperature. J Mater Sci 29:2083-2086.

Ohta M. , Shiraishi T. , Ouchida R. , Nakagawa M. , Matsuya S. (1998). Shape restoration effect associated with order-disorder transformation in equiatomic AuCu and AuCu-Ga alloys. J Alloys Compounds 265:240-248.

Ouchida R. , Shiraishi T. , Nakagawa M. , Ohta M. ( 1995). Effects of Au/Cu ratio and gallium content on the low-temperature age-hardening in Au-Cu-Ga alloys. J Mater Sci 30:3863-3866.

10.

Ouchida R. , Matsuya S. , Shiraishi T. , Nakagawa M. , Ohta M. , Terada T. (1999). Effects of variable Au/Cu ratio and Ga content on the ordering in Au-Cu and Au-Cu-Ga alloys. J Alloys Compounds 292:281-286.

11.

Phillips RW (1982). Skinner's science of dental materials. 8th ed. Philips RW , editor. Philadelphia: Saunders, pp. 248-257.

12.

Roggensack M. , Walter MH , Boning KW (1993). Studies on laser- and plasma-welded titanium. Dent Mater 9:104-107.

13.

Sjogren G. , Andersson M. , Bergman M. (1988). Laser welding of titanium in dentistry. Acta Odontol Scand 46:247-253.

14.

Togaya T. , Shinosaki T. (1999a). Introduction to laser welding in dentistry (1) . Quint Dent Tech 24:740-749.

15.

Togaya T. , Shinosaki T. (1999b). Introduction to laser welding in dentistry (3) . Quint Dent Tech 24:1471-1479.

16.

Uzuka T. , Kanzawa Y. , Yasuda K. (1981). Determination of the Au-Cu superlattice formation region in gold-copper-silver ternary system. J Dent Res 60:883-889.

17.

Wang RR , Welsch GE (1995). Joining titanium materials with tungsten inert gas, laser welding and infrared brazing. J Prosthet Dent 74:521-530.

18.

Watanabe I. , Atsuta M. , Yasuda K. , Hisatsune K. (1994). Dimensional changes related to ordering in an AuCu-3wt%Ga alloy at intraoral temperature. Dent Mater 10:369-374.

19.

Watanabe I. , Tanagawa M. , Atsuta M. (1995). New gold alloy with age-hardenability in oral cavity, Quint Dent Tech 20:105-110.

20.

Watanabe I. , Watanabe E. , Atsuta M. , Okabe T. (1997). Tensile strength of soldered gold alloy joints . J Prosthet Dent 78:260-266.

21.

Yamagishi T. , Ito M. , Fujimura Y. (1993). Mechanical properties of laser welding of titanium in dentistry by pulsed Nd:YAG laser apparatus. J Prosthet Dent 70:264-272.

22.

Yasuda K. , Ohta M. ( 1982). Difference in age-hardening mechanism in dental gold alloys. J Dent Res 61:473-479.

23.

Yasuda K. , Tendelo G. , Landuyt J. , Amelinckz S. (1986). High-resolution electron microscopic study of age-hardening in a commercial dental gold alloy. J Dent Res 65:1179-1185.