bouncy between two objects with velocity

Hello,

I'm learning Unity so i'm trying to make a game like "King of Opera". There are X players who have to push each other out of the ring but with a knockback.

I don't know how to do them pushing each other. I tried the Physic Material "bouncy" on both objects to have the push during collision but it doesn't work.

So, I use the velocity (with the variable "velo" that I increment to increment speed when the player use the key "space") of the object to move it. Maybe I have to use Force ? Is it different ?

 GetComponent<Rigidbody2D>().velocity = forward * Time.deltaTime * velo;

I think it could be great to add the vector of the object to the other like that:

 void OnCollisionEnter2D(Collision2D coll)
 {
 coll.gameObject.GetComponent<Rigidbody2D>().velocity += GetComponent<Rigidbody2D>().velocity;
 }

But that doesn't work, do you have an idea ? I tried to change the mass of my object but nothing changed...

I'm just trying to do that :.

Thanks in advance for helping.