Three-dimensional (3D) printing

1. A method of forming a 3D printed metal object comprising:

(A) depositing a build material comprising at least one metal;

(B) selectively jetting a fusing agent on the build material, the fusing agent comprising:

(i) at least one hydrated metal salt having a dehydration temperature of from about 100° C. to about 250° C., and

(ii) a carrier liquid comprising at least one surfactant and water;

(C) heating the build material and the selectively jetted fusing agent to a temperature of from about 100° C. to about 250° C. to:

(a) remove the carrier liquid,

(b) dehydrate the hydrated metal salt and form a corresponding dehydrated metal salt, and

(c) bind the build material and the selectively jetted fusing agent; and

(D) repeating (A), (B), and (C) at least one time to form the 3D printed metal object.

2. The method of claim 1 further comprising:

(E) heating the 3D printed metal object to a sintering temperature to form a metallic part.

3. The method of claim 2 , wherein the sintering temperature is from about 450° C. to about 1500° C.

4. The method of claim 2 , wherein the heating of the three-dimensional object to the sintering temperature is performed for a sintering time period ranging from about 10 minutes to about 20 hours.

5. The method of claim 2 , wherein (E) occurs in an environment containing (i) a vacuum or (ii) an inert gas, a low reactivity gas, a reducing gas, or a combination thereof.

6. The method of claim 1 further comprising:

forming a corresponding metal oxide of the hydrated metal salt after dehydrating the hydrated metal salt in (C)(b); and/or

forming a corresponding metal of the hydrated metal salt after dehydrating the hydrated metal salt in (C)(b).

7. The method of claim 1 , wherein the at least one hydrated metal salt comprises:

at least one metal cation selected from the group consisting of aluminum, magnesium, copper, zinc, iron, nickel, manganese, cobalt, molybdenum, chromium, tin, vanadium, and combinations thereof; and

at least one anion selected from the group consisting of hydroxide, carbonate, sulfate, nitrate, acetate, formate, borate, chloride, bromide, and combinations thereof.

8. The method of claim 7 , wherein the at least one hydrated metal salt is selected from the group consisting of hydrated copper nitrate, hydrated iron nitrate, hydrated nickel nitrate, hydrated manganese nitrate, hydrated cobalt nitrate, hydrated iron acetate, and combinations thereof.

9. The method of claim 7 , wherein the at least one metal in the build material is the same as the metal cation in the at least one hydrated metal salt.

10. The method of claim 1 , wherein the at least one hydrated metal salt is present in the fusing agent in an amount of from about 5 wt % to about 50 wt % based on the total weight of the fusing agent.

11. The method of claim 1 , wherein the 3D printed metal object has a fracture strength of from about 5 MPa to about 20 MPa.

12. The method of claim 1 , wherein:

the corresponding dehydrated metal salt is present in the 3D printed metal object in an amount of from about 0.2 wt % to about 20 wt % based on the total weight of the 3D printed metal object; and

a corresponding metal oxide of the hydrated metal salt is present in the 3D printed metal object in an amount of from about 0 wt % to about 10 wt % based on the total weight of the 3D printed metal object.

13. The method of claim 1 , wherein the 3D printed metal object is an at least substantially hydrated metal salt free 3D printed metal object.