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本文研究了具有等轴状、网篮状和魏氏组织的近α型Ti679合金,在450～550℃温度区间内的蠕变抗力及稳态蠕变特性。在低温区三种类型组织的蠕变抗力区别较小,魏氏组织稍高。在高温区有明显差异,而魏氏组织得到最高的蠕变抗力。在上述温度区间内,控制蠕变速率有两种机制:低温蠕变区,三种类型组织的稳态蠕变速率受温度影响较小,它们具有低的蠕变激活能和应力指数,此特征归结于硅原子——间隙原子(主要是氧)对位错的相互作用,即动应变时效效应。高温蠕变区,网篮状、魏氏组织的合金具有高的蠕变激活能和应力指数。蠕变是受细小富SiZr沉淀物阻碍位错移动速率控制的。而具有等辅状组织的合金,蠕变是受晶界滑移和较粗大的沉淀物与位错相互作用控制的。
In this paper, we study the creep resistance and steady-state creep characteristics of the nearly α-type Ti679 alloy with equiaxed, net-basket and Widmanstatten structures in the temperature range of 450-550 ℃. The difference of creep resistance between the three types of tissues in the low temperature region is relatively small, and the Wistar organization is slightly higher. There is a clear difference in the high temperature zone, and Wiesmann’s tissue has the highest creep resistance. In the above temperature range, there are two mechanisms for controlling the creep rate: the low temperature creep zone, the steady creep rates of the three types of tissues are less affected by temperature, and they have low creep activation energy and stress exponent. Attributed to the silicon atoms - interstitial atoms (mainly oxygen) on the dislocation interaction, that is, dynamic strain aging effect. High-temperature creep zone, basket-shaped, Widmanstatten alloy has high creep activation energy and stress index. Creep is controlled by the dislocation mobility that hinders the growth of small SiIF-rich precipitates. However, alloys with equivalent secondary structure, creep, are controlled by grain boundary slip and coarser precipitates and dislocations.