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许多机械装置如钟表、玩具等都采用弹簧来驱动,其能量的存储与释放是通过弹簧内部原子间距的变化来实现的。但是这种原子间距的变化(即弹性变形)所能存储的体能量密度相对很低,如何提高能量的转换效率以及材料存储的能量密度是当前材料科学理论和实验研究共同关注的一个问题。本研究利用金属钨单晶纳米线在加载时独特的孪晶变形行为,提出了一个可以在纳米尺度下高效存储与释放机械能的新原理,并据此设计了相应的纳米装置——纳米弹簧。与块体弹簧不同,本文提出的纳米弹簧通过表面原子的重构来实现能量的存储与释放。进一步的计算还表明,由于金属钨孪晶界面的移动阻力非常小,金属钨纳米弹簧的能量转换效率可以达到98%;同时该纳米弹簧存储的体能量密度可以超过钟表发条的1600倍,并具有30%的应变以及3GPa的驱动应力。
Many mechanical devices such as watches and clocks, toys and so on are driven by springs. The energy is stored and released through the change of the atomic pitch inside the spring. However, the variation of atomic distance (ie, elastic deformation) can store relatively low body energy density. How to improve the energy conversion efficiency and the energy density of material storage is a common concern in the current scientific and experimental research of materials science. Based on the unique twins deformation behavior of tungsten single crystal nanowires during loading, a new principle for efficient storage and release of mechanical energy at nanoscale is proposed. Based on this, a corresponding nanodevice, nanospring, is designed. Different from the bulk springs, the nano-springs proposed in this paper can store and release energy through the reconstruction of surface atoms. Further calculations also show that the energy conversion efficiency of metal tungsten nano-springs can reach 98% due to the very small moving resistance of the metal-tungsten twin interface; meanwhile, the energy density of the stored body of the nano-spring can exceed 1600 times of the timepiece’s clockwork With 30% strain and 3 GPa drive stress.