Where is the array being lost?

Question

Unity

Here I fill an array and fill it with prefabs

public Achievement[] ArrayAchievements;

private void Start(){
  Achievement[] ArrayAchievements = new Achievement[10];
  for(int i = 0; i < ArrayAchievements.Length; ++i){
    ArrayAchievements[i] = Instantiate(achievement) as Achievement;
    }
  Debug.Log(ArrayAchievements.Length);
  }

public void PressButtonTest(int c){
  Debug.Log(ArrayAchievements.Length);
  }

I debug displays the number of elements, I also see that the prefabs on the stage, when you click on the button (PressButtonTest) the number is 0, and in the editor I see that the array is empty, how so? Where is he lost?