Study On The Crystallization Behavior During Solidification And Performance Of Copper Based Alloy By Gas Atomization

The development of powder metallurgy technology and the technology of using micro-nano powder to synthesize bulk materials ha ve greatly improved the properties of the bulk materials in the modern industry,which have stimulated the powder demand in the industrial market.The development of 3D printing technology has further promoted the great application of powders,such as titanium,aluminum,nickel and steel-based alloy powder in the fields of aerospace,shipbuilding,automobile,metallurgy and power generation.However,the 3D printing technology has strict requirements on the powder morphology,sphericity and particle size distribution,which limit its application.Amorphous powder due to its advantages such as smooth surface could solve this problem,but the preparation of amorphous powder require s low oxygen and large undercooling surroundings and other conditions.Based on above,this paper studied the influence of the atomizer' parameters on the atomization effect by atomizing the parent alloy.The parent alloys were nominal Cu6Sn5 alloy and Cu₄₆Zr₄₂A_l7Y₅ alloy.The nominal Cu6Sn5 were obtained by smelting pure Cu and pure Sn at an atomic ratio of 6:5 and nominal Cu₄₆Zr₄₂A_l7Y₅ alloy by smelting pure Cu,pure Zr,pure Al and pure Y at an atomic ratio of 46:42:7:5.Thus Cu6Sn5 alloy powders and amorphous Cu₄₆Zr₄₂A_l7Y₅ powders were successfully prepared.The structures of these powders were analyzed by XRD,DSC and SEM.And finally,the new applications of these aerosolized powders were discussed.Experimental results are as follows.For metallic materials or alloy with medium or low melting point,it achieved the best atomization effect when inner diameter of the nozzle was 1.5 mm,the auxiliary atomizing pressure P1 was 0.07 MPa and the dominating atomization pressure P2 was 0.15 MPa.In this experiment,Cu-Sn alloy powder containing Cu6Sn5,Cu3 Sn and Sn was successfully prepared.The larger powder contained more Cu 3Sn and Sn phase while smaller particle size powder contained more Cu6Sn5 phase,which was related to multi-site nucleation,surface nucleation and selection precipitation of phases;It was found that the surface of the alloy powder had a significant microstructure effect on the size of powder and that the powder could be transformed into single-phase Cu6Sn5 compound powder by appropriate heat treatment.The compound powder could be used in flip-chip to get effective interconnection.For alloy materials with high temperature melting poin t,it achieved the best atomization effect when inner diameter of the nozzle was 1.5 mm,the auxiliary atomization pressure P1 was 0.07 MPa and the dominating atomization pressure P2 was 0.2 MPa.In this experiment,Cu₄₆Zr₄₂A_l7Y₅ powder was successfully prepared.The particle size distribution of the powder was mostly concentrated between 70 ?m and 200 ?m with an average particle size of about 120 ?m.And 160 ?m was the critical size of the boundary between amorphous and crystalline powders.With the decrea se of powder particle size,the appearance of lumps,mixed pattern of massive and rivers,the smooth morphology on the powder was found,which was also related to multi-site nucleation,surface nucleation and selection precipitation of phases.The hardness of Cu₄₆Zr₄₂A_l7Y₅ alloy powders were closely related to the crystalline and amorphous states,but not related to the size of the powders.In addition,the amorphous Cu₄₆Zr₄₂A_l7Y₅ powders could also be used for effective interconnection in the flip-chip and the fracture of most joints showed mixed modes of ductile fracture and brittle fracture.