Prediction of High-temperature Creep Deformation for Precipitation Hardened Aollys

沉淀硬化被认为是一种既适用于室温又适用于高温的有效强化方法。人们对沉淀硬化合金的高温变形进行了大量的研究。最近，Arzt和Rosier提出了一个基于粒子和位错相互作用的弥散强化合金高温变形模型。变形过程中的速率控制步骤是热激活的位错从粒子的出发侧脱离。分散粒子是热稳定粒子。然而，众所周知，沉淀硬化合金存在奥斯特瓦尔德成熟。在高温变形过程中，析出相在高温下长大，析出相的弥散参数发生变化。为了阐明这种Ostwald成熟对析出硬化合金高温变形的影响，本文提出了一种利用析出硬化合金Ostwald成熟预测高温变形行为的方法。将理论计算结果与Al-1.03质量% Si合金的实验结果进行了比较。对Al-1.03质量% Si合金的阈值应力、Si析出相弥散参数和应力-应变曲线的时间依赖性进行了评价。利用该预测方法计算了温度从473K到723K对变形行为的影响。研究了Al-Si析出相奥斯特瓦尔德成熟对Al-Si析出硬化合金高温变形行为的影响，结果与实验结果吻合较好。

Precipitation hardening has been considered to be an effective strengthening method not only at room temperature but also at high temperatures. Many investigations have been carried out on high temperature deformation of precipitation hardened alloy. Recently, Arzt and Rosier have proposed a model for the high temperature deformation of dispersion strengthened alloys based on an attractive interaction of particle and dislocation, In that model. the rate controlling step in the deformation process is the thermally activated detachment of a dislocation from the departure side of a particle. The dispersion particles are thermal-stable particles. However it is well known that there is Ostwald ripening in precipitation hardened alloy. The precipitates grow up at high-temperature and the dispersion parameters of the precipitates change during high-temperature deformationIn order to clarify the influence of this Ostwald ripening on high-temperature deformation in precipitation hardened alloys, this work proposed a predicting method of high-temperature deformation behavior with Ostwald ripening of precipitates for precipitation hardened alloy. The theoretical calculations were compared with the experimental results for Al-1.03 mass% Si alloy. The evaluation was carried out of the time dependence of the threshold stress, dispersion parameters of Si precipitates and stress-strain curves for Al-1.03 mass% Si alloy. The effects of temperature raging from 473K to 723K on deformation behaviors were calculated by this prediction method. The influence of Ostwald ripening of Si precipitates on high-temperature deformation behaviors was revealed in the Al-Si precipitation hardened alloy, The results were in good agreement with experimental ones.