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采用显微维氏硬度计,X射线衍射仪,扫描电镜和电子探针技术,研究试验用牙科低金含量银钯合金的时效强化行为及机制。经900oC固溶处理30min后的合金试样分别在400和600oC进行恒温热处理。结果表明,在400oC恒温热处理的合金硬度随时效时间的延长单调升高。而在600oC恒温热处理的合金维氏硬度迅速提高并在时效处理2min时达到最大值,之后随时间的延长而单调下降并保持在1600-1700MPa。XRD结果表明,经时效处理后,2组样本均有明显的沉积相出现。扫描电镜和电子探针结果显示,在600oC时效处理2min的样品有沉积颗粒出现。然而,时间-半高宽曲线却表明时效处理后合金硬度的提高与相变产生的应变有关,故而不能认为400oC恒温热处理时产生的相变能提高合金硬度。
Micro-Vickers hardness tester, X-ray diffraction, scanning electron microscopy and electron probe technique were used to study the aging strengthening behavior and mechanism of dental low gold content silver-palladium alloy. After 900oC solution treatment 30min after the alloy samples were 400 and 600oC for heat treatment at constant temperature. The results show that the hardness of alloys annealed at 400oC increases monotonically with the aging time. However, the Vickers hardness of alloy annealed at 600oC increased rapidly and reached the maximum at 2min aging treatment, then monotonically decreased and maintained at 1600-1700MPa with the extension of time. XRD results showed that after aging treatment, obvious depositional facies appeared in both samples. Scanning electron microscopy and electron probe results showed that samples aged at 600oC for 2min had sedimentary particles. However, the time-FWHM curve shows that the increase of the hardness of the alloy after aging treatment is related to the strain caused by the phase transformation. Therefore, it can not be considered that the phase transition during 400oC constant temperature heat treatment can improve the alloy hardness.