Abstract: Glass, a main component of lunar soil, is widely mixed in various forms like particles and agglutinates of small sizes in lunar soil and has good spatial applicability. The good glass-forming ability of lunar soil makes it the preferred raw material for the preparation of space glass materials. However, due to the lack of micro and nano sample preparation and detection methods, the mechanical properties of lunar glasses are rarely reported before, which seriously restricts the service evaluation of such glassy materials. In this study, the microstructures and mechanical properties of five typical Chang'e-5 lunar glassy particles are systematically studied by means of micro and nano sample preparation and mechanical testing combined with transmission electron microscopy (TEM) characterization. The results show that the lunar glasses have flexible and changeable (homogeneous to nano scaled inhomogeneous) amorphous structures and broad controllable mechanical properties (hardness ranges from (6.1±0.4)GPa to (8.4±0.2)GPa, modulus ranges from (48.5±1.9)GPa to (88.4±2.4)GPa). In addition, there is a marvelous decoupling phenomenon between the hardness and modulus of the lunar glasses, i.e., the rejuvenation process (heating them up to the supercooled liquid region and then cooling down to room temperature at fast cooling rates) greatly reduces the modulus while has much weaker effects on the hardness, which is attributed to the deformation mode changed from densification to shear flow. The rejuvenation process will induce volume expansion and inhomogeneous structure in the lunar glasses, which will facilitate such deformation change, leading to hardening effects. The results can provide guidance for the research and development of high-performance glassy materials for space application.

Key words: lunar glasses, inhomogeneous, hardness, modulus, decoupling, rejuvenation