尺寸稳定性是指材料在长期贮存或者服役环境下保持原始尺寸不变的能力。陀螺仪、星敏感器、光学观瞄设备等角度、速度、位置传感器的关键零部件对材料的微变形十分敏感,材料的尺寸不稳定性问题已经成为制约装备精度的“卡脖子”问题。国外自20世纪70年代从金属的热处理、预拉伸变形等组织调控方法入手做了较深入的研究,我国关于材料尺寸稳定性的研究十分薄弱,主要集中于残余应力的影响上,工程效果不明显。本文介绍作者及其团队长期从事材料尺寸稳定性研究的体会与成果,包括长期贮存(无应力)条件下尺寸稳定性的表征新方法,基于该方法发现了铝合金相稳定、组织稳定及其各向异性的基本规律;总结了铝基复合材料尺寸稳定性设计的基本原理和基于增强体弥散度的设计思路;高尺寸稳定性的光学级、仪表级SiC/2024Al复合材料的微观构型特征及其在实际工程中应用的效果。理论和实践表明,仪表精度及其精度稳定性取决于材料的尺寸稳定性,而材料的稳定性首要因素是其内禀变形特性,而残余应力是次要的。本工作也表明,尺寸稳定性原理的应用对于精密轴承一类高精度零件的技术提升也将有启发性。

Dimensional stability refers to the materials' ability to maintain their original size during long-term storage or under service conditions. The key components of the angle, velocity and position sensors, such as the gyroscopes, star sensors and optical observation devices, are extreme sensitive to the micro-deformation of the materials, and the dimensional instability of the present materials has become to be the bottleneck problem that restricts the accuracy of the equipment. Deep research has been carried out abroad from the aspect of the microstructure modification by heat-treatment and pretension deformation treatment of metals since 1970s. However, the domestic research on the dimensional stability is rather weak, which was mainly focused on the effect of the residual stress, and the corresponding engineering application effect is not pronounced. In the present work, the research experience and main results of the authors and coworkers on dimensional stability for decades have been introduced, including novel characterization method of dimensional stability during long-term storage (without stress), and the basic evolution process of the phase-stability, microstructure-stability and the anisotropy behavior of the Al alloys, which was revealed by the novel characterization method. Furthermore, the basic design principles of high dimensional stability and the design ideas based on the dispersivity of reinforcements of the Al matrix composites have been introduced. Moreover, the microstructure characters and the application effect in practical engineering of the high dimensional stability optical-grade and instrument-grade SiC/2024Al composites have been described. Based on the theoretical analysis and the practice effects, it indicates that the accuracy and accuracy stability of the instruments is mainly depended on dimensional stability of the used materials, and the dimensional stability of the materials was mainly affected by its intrinsic deformation characteristics, while the effect of the residual stress was subordinate. The present work also indicates that the application of the dimensional stability principle is also instructive to the technology upgrading of the high precision components, such as precision bearings.