WE CLAIM:
1. A method comprising:
associating a plurality of preform plies to define a preform, wherein a first preform ply and a second preform ply of the plurality of preform plies have different average pore sizes; and
subjecting the preform to chemical vapor infiltration (CVI) to define a densified ceramic matrix composite (CMC) structure.
2. The method as claimed in claim 1, wherein the first preform ply has a first average pore size, wherein the second preform ply has a second average pore size and wherein second average pore size is greater than the first average pore size.
3. The method as claimed in claim 1, wherein the first preform ply is a center preform ply having first average pore size, wherein the second preform ply is an outer surface preform ply defining an outer surface of the preform, and wherein the second preform ply has a second average pore size greater than the first average pore size.
4. The method as claimed in claim 1, wherein the plurality of preform plies includes a third preform ply, wherein the second preform ply is disposed at a first side of the first preform ply, wherein the third preform ply is disposed at a second side of the first preform ply, and wherein the second preform ply and the third preform ply each have larger average pore size than an average pore size of the first preform ply.
5. The method as claimed in claim 1, wherein a preform defined by the plurality of preform plies is a solid structure, wherein the plurality of preform plies includes a center preform ply, a first set of preform plies from the center perform ply to a preform ply defining a first outer surface of the preform having increasing average pore sizes, and a second set of preform plies from the center perform ply to a preform ply defining a second outer surface of the preform having increasing average pore sizes.

6. The method as claimed in claim 1, wherein the preform is a hollow structure preform, wherein the plurality of preform plies of the preform define a sidewall of the hollow structure preform, wherein the plurality of preform plies includes a center preform ply, a first set of preform plies from the center perform ply to a preform ply defining an outer surface of the hollow structure preform having increasing average pore sizes, and a second set of preform plies from the center perform ply to a preform ply defining an inner surface of the hollow structure preform having decreasing average pore sizes.
7. The method as claimed in claim 1, wherein the preform is a hollow structure preform, wherein the plurality of preform plies of the preform define a sidewall of the hollow structure preform, wherein a certain preform ply of the plurality of preform plies that defines an inner surface of the hollow structure preform has a smallest average pore size of the plurality of preform plies, and wherein preform plies of the plurality of preform plies in a succession of locations from a location of the certain preform ply to a location of a preform ply that defines an outer surface of the hollow structure preform have increasing average pore sizes.
8. The method as claimed in claim 1, wherein the method includes performing a process for fabricating one or more preform ply of the plurality of preform plies.
9. The method as claimed in claim 1, wherein the method includes controlling an average pore size of one or more preform ply of the plurality of preform plies, and wherein the controlling an average pore size of the one or more preform ply includes adding or reducing an amount of filler used during a pyrolysis process for fabrication of one or more preform ply of the plurality of preform plies.
10. The method as claimed in claim 1, wherein the method includes controlling an average pore size of one or more preform ply of the plurality of preform plies, and wherein the controlling an average pore size of the one or more

preform ply includes controlling a characteristic of a pore former used during fabrication of one or more preform ply and the plurality of preform plies.
11. The method as claimed in claim 1, wherein the method includes shaping the preform into a shape of a turbine component, and providing one or more center preform plies of the plurality of preform plies to have smaller average pore sizes than one or more outer surface preform ply of the plurality of preform plies.
12. A structure comprising:
a plurality of preform plies associated together to define a preform;
wherein a first preform ply and a second preform ply of the plurality of preform plies have different average pore sizes.
13. The structure as claimed in claim 12, wherein the second preform ply has a larger average pore size than the first preform ply.
14. The structure as claimed in claim 12, wherein the first preform ply is a center ply having a first average pore size wherein the second preform ply has a second average pore size, the second average pore size being larger than the first average pore size.
15. The structure as claimed in claim 12, wherein the plurality of preform plies includes a third preform ply, wherein the second preform ply is disposed at a first side of the first preform ply, wherein the third preform ply is disposed at a second side of the first preform ply, and wherein the second preform ply and the third preform ply each have a larger average pore size than an average pore size of the first preform ply.