含裂纹成分连续过渡梯度材料高温时间相关损伤破坏

项目名称： 含裂纹成分连续过渡梯度材料高温时间相关损伤破坏

项目编号： No.50871025

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 建筑科学

项目作者： 许富民

作者单位： 大连理工大学

项目金额： 30万元

中文摘要： 梯度材料是一种成分连续或逐级变化，具有优异性能的非均匀材料，多种梯度材料已经开发出来了，在工程上已经有了一些应用，并且也解决了一些实际问题，但对含缺陷梯度材料时间相关高温损伤破坏还很少，对梯度材料的理解还远远不够。为推进梯度材料发展和在高温环境应用，本项目提出采用Al/Al-Cu成分连续过渡梯度材料作为研究对象，针对含裂纹成分连续梯度材料损伤破坏进行研究，通过和时间相关断裂力学参量进行关联，建立扩展速率的表述方法。研究了采用双流浇注连续铸造和粉末冶金法制备成分连续过渡梯度材料。采用粉末冶金法制备的三点弯曲试样进行蠕变裂纹扩展工作。通过SEM、EPMA、XRD、TEM等方式的检测结果表明，通过热处理进行成分分布调整，可获得具有一定成分分布的梯度区。蠕变裂纹扩展采用两种加载方式：恒位移点加载和恒载荷加载。目前的研究表明蠕变裂纹扩展力学控制参量为σt、断裂力学控制参量为C*，材料成分分布方式通过改变材料局部性能影响蠕变裂纹扩展。在辅助工作中也得到了一系列有意义的成果，对Al2O3、AlN以及B4C的研究表明，这些复合陶瓷第二相存在方式，通过不同方式对复合陶瓷性能产生起作用。

中文关键词： 梯度材料；蠕变裂纹；Al-Cu；粉末冶金；热处理

英文摘要： Functionally graded materials (FGMs) are special inhomogeneous materials with superior properties due to continuous or stepwise components distribution. A variety of FGMs have been developed. Some of them have been applied in engineering, and also resolved a number of practical problems. But until now, there's still a little research performed on high temperature time-dependent damage of FGM with crack. In fact, the understanding of FGM is far from enough. In order to promote the development and application of FGM in high-temperature environment, Al/Al-Cu FGM with continuous components distribution is selected as research material. Main task are the high temperature damage analysis of continuous components distribution FGM containing crack. Express method of creep crack growth rate are established upon present research works by time-dependent fracture mechanics parameters of C*. The results can provide fundmental data for accurate prediction of residual life of ethylene cracking furnace tube after the cavity formation due to long time carburization. The research project has important theoretical and practical significance. FGM with continuous gradient transition region fabricated by double pouring continuous casting and powder metallurgy technique. Creep crack growth was carried out with three-point bend specimens fabricated by powder metallurgy technique. The results of SEM, EPMA, XRD, TEM, etc showed that FGMs with specific distribution zone of the constituents could be adjusted by heat treatment. Two load mode of creep crack growth experiments were selected: constant load and constant displacement point. The current results show that the control parameter of mechanics is σt and control parameters of fracture mechanics is C*. Local property changes due to the profiles of components distribution changing which has great influence on the properties of creak crack growth of FGM. A series of meaningful results in the auxiliary work showed that second phases exist in defferent ways in composite ceramics, Al2O3, AlN, and B4C, and the performance of these second phases are in different modes.

英文关键词： FGM; Creep crack; Al-Cu; Powder metallurgy; Heat treatment