$5.$ Explosive welding uses a controlled $\_$ to accelerate one of the workpieces towards the other at a high velocity, creating a $\_$ under high$-$pressure conditions, ideal for joining $\_\_\_$ materials. $($Options: detonation, explosion, vacuum, bond, gap, dissimilar, similar$)$

$6.$ Ultrasonic welding utilizes high$-$frequency $\_$ waves to join materials, a process that is particularly effective for $\_$ and $\_$ without requiring additional $\_$ or fillers. $($Options: sound, vibration, light, thermoplastics, metals, ceramics, heat$)$