Can I buy an Ipad in USA and use it as a cellphone in Argentina?

An iPad has no cell phone capability.

Since you can purchase an iPad with cellular, depending on the carrier, you may be able to send text messages in lieu of a cellphone.

You can't use the iPad a cell phone, period. The iPad cannot place or receive cellular calls, or send/receive SMS directly on its own. The Cellular option is only for data/internet access.

You are welcome