Earth-boring tools and methods of forming earth-boring tools

1. A fixed-cutter earth-boring tool, comprising:

a first blade substantially comprising a first material having a first elastic modulus at a temperature, the first blade carrying a first plurality of cutting elements and having a first stiffness; and

a second blade substantially comprising a second material having a second elastic modulus at the temperature, the second blade configured to have a second stiffness different from the first stiffness.

2. The fixed-cutter earth-boring tool of claim 1 , wherein:

the first blade is a primary blade;

the second blade is a secondary blade; and

the first stiffness is higher than the second stiffness.

3. The fixed-cutter earth-boring tool of claim 1 , wherein the first blade is configured to deflect a first distance under a selected load, and wherein the second blade is configured to deflect a second distance under the selected load, the second distance being greater than the first distance.

4. The fixed-cutter earth-boring tool of claim 3 , wherein the second distance is 0.001 inch (0.0254 mm) or more under a load on the blade of 1000 lbs.

5. The fixed-cutter earth-boring tool of claim 4 , wherein the second distance is 0.005 inch (0.127 mm) or more under a load on the blade of 1000 lbs.

6. The fixed-cutter earth-boring tool of claim 1 , wherein at least one surface of the second blade defines an open space and wherein the second blade is configured such that a force operative on the second blade causes a change in volume of the open space.

7. The fixed-cutter earth-boring tool of claim 1 , wherein the first blade has a first average transverse thickness, and the second blade has a second average transverse thickness, the second average transverse thickness different from the first average transverse thickness.

8. The fixed-cutter earth-boring tool of claim 1 , wherein the second blade carries a second plurality of cutting elements.

9. The fixed-cutter earth-boring tool of claim 8 , wherein at least one cutting element of the second plurality of cutting elements comprises a tungsten carbide insert, a diamond insert, an impregnated insert, a polycrystalline diamond compact, or a thermally stable product.

10. The fixed-cutter earth-boring tool of claim 1 , wherein the second blade carries a depth-of-cut limiter or a wear pad.

11. A method of forming an earth-boring tool, comprising:

forming a bit body having a plurality of blades, at least a first blade of the plurality substantially comprising a first material having a first elastic modulus at room temperature, at least a second blade substantially comprising a second material having a second elastic modulus at room temperature, the second elastic modulus higher than the first elastic modulus, the at least a first blade having a stiffness different from a stiffness of at least a second blade of the plurality; and

providing at least one cutting element on at least one of the plurality of blades.

12. The method of claim 11 , wherein forming a bit body having a plurality of blades comprises providing a metal into a mold, the mold configured to define at least a surface of the bit body.

13. The method of claim 12 , wherein forming a bit body having a plurality of blades comprises providing a metal into a mold having a plurality of cavities, each cavity configured to define at least a surface of a blade, wherein at least one cavity has an average transverse thickness different from an average transverse thickness of another cavity.

14. The method of claim 11 , wherein providing at least one cutting element on at least one of the plurality of blades comprises attaching at least one of a tungsten carbide insert, a diamond insert, an impregnated insert, a polycrystalline diamond compact, or a thermally stable product to at least one of the plurality of blades.

15. The method of claim 11 , further comprising forming an open space within at least one of the plurality of blades.