Mixed amorphous-nanocrystalline cobalt phosphorous by pulse plating

► Mixed amorphous-nanocrystalline electrodeposited Co-P alloy films. ► High current density pulse plating enables deposition of low P alloy. ► Alloy displays relatively high thermal stability. ► Strong increase of hardness by short annealing at 400 °C ► Thermal treatment induced cracking impairs protective properties.