I applied T6 heat treatment on A356 alloy. Surprisingly, the compression test graphs showed elastic modulus of 97 Gpa which seems odd to me. The yield stress of the alloy calculated to be 276 Mpa which is reasonable. The reported E in most of the works varies in range of less than 72 Gpa. I think that one reason could be higher concentration of silicon particles in compression samples as they were machined from a casting rod. A casting rod with daimeter of 30 mm turned to 8 mm and because the center of the rod is the last area that solidifies, it has a high concentration of Si particles and this increases the mechanical strength of the compression samples. But, I don't think that such a high modulus can be only because of this reason.