The alloy phase diagram is an important diagram reflecting the equilibrium crystallization characteristics of the alloy, as well as the relationship between the alloy composition and the balance structure, and the performance of the alloy mainly depends on the composition and structure of the alloy, so the performance of the alloy can be qualitatively judged according to the ( ).
选项：

A:Composition of alloy;
B:Structure of alloy;
C:Phase diagrams;
D:Composition and structure of alloy