The effects of superimposed ultrasonic vibration on the plastic deformation of 99.99% pure polycrystalline Cu are studied both during (temporary) and after (residual) the application of ultrasound (US) using deformability measurements acquired from an automated wire bonding machine and microhardness testing. It is found that if ultrasonic irradiation is applied during the deformation of the 100 μm diameter Cu free air balls (FABs) the Cu becomes softer with increasing US power compared to Cu FABs that are deformed without US. When comparing this temporary acoustic softening of Cu to that of Au, it is found that the amount of softening is similar between the two materials. After the US is turned off, a residual acoustic softening remains. This residual softening effect increases with increasing the US power. With residual acoustic softening, a maximum increase of 13% in deformability is measured for Cu during wire bonding compared to a maximum increase of 8% for Au during wire bonding. Stronger residual acoustic softening effects are obtained in Cu than in Au with a maximum decrease in microhardness of 19% and 9%, respectively. Dynamic annealing and dislocation theory are used to explain both the temporary and residual effects of US on the deformation of Cu and Au.

Azo molecular glass (IAC-4) microspheres with a monodispersed diameter over ten microns were fabricated by microfluidics and unique shape manipulation was achieved based on their fascinating photoinduced deformation behaviour. After irradiation with a polarized laser beam (λ = 488 nm), the IAC-4 microspheres were transformed into uniform mushroom-like particles, and their three-dimensional (3D) asymmetric shapes were precisely manipulated by adjusting the irradiation time and the polarization state of light. By observing the particle morphology in three orthogonal views (top view, front view and side view) by scanning electron microscopy (SEM), the photoinduced deformation behaviour of the ten-micron-sized particles was comprehensively revealed in the 3D space for the first time. It was observed that the photoinduced deformation asymmetrically occurred on the upper part of the microspheres due to the strong optical absorption of the azo chromophores. Besides, the deformation manner of the upper part was decided by the direction of the electric vibration of the refracted light. This work not only depicts a clear picture of the photoinduced deformation behaviour of the ten-micron-sized azo particles upon polarized light irradiation, but also provides a new method to controllably manipulate the particle shape from spheres to complex 3D architectures.

The effects of superimposed ultrasound vibration on plastic deformation of gold are studied both during and after the vibration using an ultrasonic ball bonding machine. It is found that when ultrasonic irradiation is applied along with mechanical force, the metal is softer than when deformed without the vibration. After ultrasound is turned off, the deformed metal remains softer if previously deformed with ultrasound. Possible mechanisms for the acoustic residual softening are discussed as compared to residual hardening. The acoustic residual effect is attributed to the net balance between ultrasound’s dynamic annealing and its potential opposing effect on activating and multiplying dislocations.