摘要
高温钛合金是先进航空发动机压气机应用的理想材料，代替钢或镍基高温合金，可以显著提高发动机的推重比和服役性能。随着钛合金使用温度的提高，高温蠕变抗力越来越成为影响其使用温度和使用寿命最关键的力学性能。在400-600℃的温度范围内，钛合金的蠕变变形一般受位错攀移机制所控制，蠕变激活能近似等于有效扩散激活能，因此，扩散是影响钛合金高温蠕变抗力的最主要因素。杂质元素Fe在钛合金中具有反常大的扩散能力，是Ti自扩散系数的10^3～10^5倍，在Ti中的扩散可能受离解扩散机制所控制。钛合金中的微量Fe同时会显著促进Ti的自扩散，提高位错攀移速率，从而降低蠕变抗力。为了改善高温钛合金的蠕变性能，需要严格控制原材料如海绵钛和中间合金中杂质Fe的含量。
High temperature titanium alloys were idea materials for advanced aero engine compressor use due to their excellent contribution to the spectacular progress in thrust-to-mass ratio and operating performances, which had been achieved through the substitution of titanium alloys for steel or Nibased superalloys. With increasing the operating temperature of titanium alloys, creep resistance becomes the most important mechanical property which may affect the operating temperature and service lifetime. Over the temperature range from 400℃ to 600℃, creep deformation of titanium alloys is primarily controlled by dislocation climb mechanism, the activation energy of creep is close to the activation energy of effective diffusion. Therefore, diffusion plays an important role in dominating creep resistance for high temperature titanium alloys. The impurity iron has an abnormal high diffusion ability which is 103-105 times as large as that of self-diffusion in titanium, and may be attributed to the dissociative diffusion mechanism. Meanwhile, trace iron may promote the self-diffusion of Ti, thus may increase the dislocation climb rate and reduce the creep resistance. In order to improve the creep resistance of high temperature titanium alloys, the content of impurity iron must be carefully restricted in the raw materials such as titanium sponge and master alloys.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2009年第8期84-88,共5页
Journal of Materials Engineering
关键词
高温钛合金
杂质元素Fe
扩散行为
蠕变抗力
high temperature titanium alloy
impurity iron
diffusion behavior
creep resistance
