The wires in the connection cable of the oven are normally copper. They may have a coating. I looked at specifications for that oven. It appears that the wires in the pigtail connection are UL 3321 wires. These are Underwriters Laboratory approved wires for the connection of that range to the junction box. They appear to be a stranded, fully annealed tinned copper conductor.
I understand your concern about safety in regards to the connection of this oven to the power supply. I recommend that you have an electrician connect the oven to the junction box to make sure that the proper connectors are used.
I hope that this information helps. If you need more assistance, reply with additional details.