| As an advanced material preparation technology, spray deposition has an advantage in producing high performance alloys and metal matrix composites. However, the workability and mechanical properties of spray deposited preforms are poor owing to the porosity formed during the deposition processing. So, further densification and plastic deformation treatment are needed to prepare fully dense products with high mechanical properties. Due to the porosity, the forming property of spray deposited preforms is poor. Thereby, processed directly by tranditional plastic working, such as forging and rolling, spray deposited preforms are easy to crack during the processing, because of stress condition. Resultingly limitation of equipment, it is difficult to densify the spray deposited preforms with large dimension by extrusion. According to shapes of spray deposited preforms, different densification technologies of preforms with large dimension and sheets were investigated respectively. As for spray deposited preforms with large dimension, the process parameters of Sequential Motion Compaction (SMC) were optimized by using finite element method. Based on SMC, a novel technique named Sequential Motion Compaction with Temperature Gradient (SMC-TG) was developed firstly. And as for spray deposited sheets, the Ceramic Rolling (CR) and Frame-Confined Rolling (FCR) were studied detailedly. The main researches in this study are as follows:(1) A study on the behavior of hot compression of spray-deposited 5A06 aluminum alloy was performed. The experimental results show that the flow stress of spray deposited 5A06 aluminum alloy during the hot compression decrease with the enhancement of deformation temperature and the decrease of strain rate. At the higher deformation temperature, stress-strain curves are gentle and there are no obvious yield points on curves. With comparing, at lower temperature, stress-strain curves are ascending curves, but no peak values on curves.A constitutive equation was established by analyzing the relationships of the flow stress and the strain and the deformation temperatures and strain rates. The proposed equation gives a good agreement with the measured values, which consequently can be as the numeric-simulated flow stress model of spray-deposited 5A06 aluminum alloy during hot deformation. In this study, the changes of the microstructure and the hardness have revealed the relationships of temperatures and the strain rates.A theoretic relationship to relative density and high reduction was established in the single axial compress, the results of FEM show that the theory values and the FEM results give a good agreement with the measured values.(2) By the finite element software, the effects of the different process parameters on the deformation and densification in the SMC process were researched. The results show that the two face SMC is needed and the reasonable temperature is 450℃～500℃, the reasonable velocity is 0.5～1.0mm/s.(3) Based on SMC, the novel technique named as"Sequential Motion Compaction with Temperature Gradient (SMC-TG)"is applied. The densification and evolution of microstructure during SMC-TG were investigated. The results of SMC and SMC-TG were compared. As a result, the SMC-TG process could improve the densification of preform. When the height reduction is 25%, the distribution of relative density along height direction is homogeneous, and the unitary relative density is above 95%. Compared with SMC process, the lateral flow on bottom of preform is increase, the effect on reduction of porosity is attained, and the bottom of preform has higher relative density. SMC-TG could improve the microstructure of spray deposited preforms, by compared SMC with SMC-TG. When the height reduction is 25%, the preform processed by SMC-TG is compact basically, and there are many pores in SMC preform. Due to SMC-TG could densify the spray deposited preform effectively, the mechanical property is improve obviously. From the results of fractography, after SMC-TG, the pore spaces have been eliminated, and at the same time, the bonding between SiC particles and matrix has been reformed.(4) The effects of processing conditions during"Ceramic Rolling"technique, such as rolling method and the size of preforms, were investigated. To meet the needs of forming property, the 180°turning rolling method must be adopted, and the best size of preform is L×B×H=30×30×8mm.The densification and deformation of spray deposited sheets during CR were investigated. Comparing with traditional rolling, due to the ceramic particles serve the function of rejection of metal flow, a remarkable lower elongation is attained for the ceramic-rolled samples, and tension strain which can induce the occurrence of crack is reduced. It is in favor of the densification process of preform. During traditional rolling, transversal cracks usually occur on the surface of preform when the thickness reduction is up to 26.5%. But in the processing of ceramic rolling, no cracks appear while the thickness reduction is 60%. The CR technique could improve the rolling forming property of spray deposited preform. After CR, it could attain favorable mechanical property at room temperature by direct rolling. The tensile strength and elongation of 8009Al/SiCp is 505.0MPa and 6.5% respectively.The densification and plastic deformation behaviors and the fracture behaviors of the as-spray deposited porous performs are related with the effects of particulate characteristics during CR process. The preform could attain best effect of densification and forming property by using the Al2O3 particle with the size of about 200 meshes.(5)The processing conditions of FCR and the influence factors on the densification effect were analyzed. The experimental results show that the FCR technique can greatly improve the workability of spray deposited preforms and avoid cracks whcich easily occur during the conventional rolling processing. The best gaps size in length and width wereθB=4.0～6.0% andθL=7.5～10.0% for the densification and workability of spray deposited preforms.The densification and deformation mechanism, evolution regularities of the pores and microstructures during the FCR processing are discussed. The mechanical properties of the as-rolled sheets were examined. At the beginning of the rolling processing, the distribution of thickness reduction in the as-rolled sheets were not uniform, the thickness reduction on the surface layer of the sheet was smaller than that in the center layers. When the preforms fully filled the frame, the thickness reduction distribution will tend to be uniform. The densification rate of the surface layer of the preforms was the most fast. During rolling of the 8009Al/SiCp preforms, the SiC particles easily break up into finer pieces and the distribution state tend to be more uniform. The relative density of spray deposited preform could attain 99.0%, and the preforms can be direct rolled without crack. The tensile strength and elongation of 5A06 aluminum alloy is 340.0MPa and 12.0% respectively, and for 8009Al/SiCp composite is 450.0MPa and 9.5% respectively.
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