This image shows a turbine shaft and wheel with fairly serious impact damage. If you look at the wheel itself, you can see that the blades are uneven and chipped, and that the surface of the wheel has become severely pitted.
In this case, the damage was caused by major engine failure, which allowed foreign objects and melted deposits of aluminium to get into the turbine housing.
The turbine wheel in a turbocharger spins at high speeds, and even small foreign objects can cause serious damage. In this case, the deposits caused serious impact damage to the turbine, roughing up the surface of the metal, whilst chipping away and shearing off pieces of the wheel itself.
Any number of things can lead to engine failure, and the subsequent damage it causes to your turbocharger can be terminal! Unfortunately, this turbine wheel is well beyond repair, and the only course of action was to replace the turbine shaft and wheel with a new one.