Returning dynamic array from the function

[m0rph]

I tryed to learn how arrays works and found another strange thing:

import std.stdio;

int[] create()
{
	int[5] a1 = [ 10, 20, 30, 40, 50 ];
	int[] b1 = a1;
	writeln("b1: ", b1);
	return b1;
}

void main()
{
	int[] a2 = create();
	writeln("a2: ", a2);
}

Result of execution:
b1: [10, 20, 30, 40, 50]
a2: [-142625792, 32767, 4358059, 0, 5]

Please explain what's wrong with this code? Why variable a2 
contains crap? Is this another dmd/druntime bug or I missed 
something?