The Study Of The Microstructure And Mechanical Properties Of Bulk Metallic Materials (Ti, Al, Cu) Prepared By Thermal Mechanical Powder Consolidation

Powder thermal mechanical consolidation is a kind of less or no cutting technology in the manufacturing process of metal profiles and parts and has some advantages such as high performance, low cost and near net shape. The bulk materials and parts of titanium, aluminum, copper and their alloys produced by powder thermal mechanical consolidation have strong market competition and great attention owing to low cost and good performance in the application of aerospace, automotive and other fields. However, the comparison of the microstructure and mechanical properties had been investigated by the samples of the same metal material prepared by different powder compact consolidation, and the influence factors of interparticle boundaries transformation have no intensive study in the process of powder thermal mechanical consolidation, such as temperature and oxide film. This paper had studied the effect of preparation process on microstructure and mechanical properties through characterizing by the bulk materials of Ti, Ti-6Al-4V, Al, Cu and rocker arm of engine produced by powder compact forging(PCF), powder compact extrusion(PCE) and spark plasma sintering(SPS). The effect of consolidation process on interparticle boundaries transformation had been intensive studied according to the analysis of the microstructure and tensile fracture behavior. The effect of the oxide film condition had been investigated in respect of material forming characteristics, microstructure changing rules and mechanical properties. This research results may have great importance to further understanding the influence of different consolidation process on the interparticle boundaries transformation, and have great engineering guidance value on the improvement of powder thermal mechanical consolidation.Firstly, the microstructure, mechanical properties and interparticle boundaries transformation of powder compact forging titanium and Ti-6Al-4V, and powder compact extruding titanium and Ti-6Al-4V had been studied under the medium strain rate from 10-4 to 10-1 s-1. The results showed that these samples had lamellar structure and good consolidation condition as a result of the rapid melting of oxide film and the new interfaces bonded together. These samples were very sensitive to the change of strain rate, and the number and volume fraction of holes were increased near the fracture section with the increase of strain rate.Secondly, this chapter has investigated the hardness and strength of the Ti and Ti-6Al-4V rocker arm produced by powder compact forging, and discussed the consolidation condition of these samples. The feasibility and economic value of near-net forming had been studied through powder compact forging in the fields of automobile and aircraft engine parts. These resultes showed that these rocker arms had high level consolidation condition, high tensile strength, large hardness and good ductility. The hole defects were rarely produced in the tensile test at higher strain rate. The ductility of these samples were decreased due to the dispersed distribution of texture on the cross section of the vertical direction of the forging.Thirdly, this chapter was investigated the difference of microstructure, mechanical properties and fracture behavior using the aluminum and copper samples having the different affinity with oxygen prepared by SPS consolidation process. The effect of oxide film on the grain growth, interparticle boundaries transformation, and mechanical properties had been discussed in the powder thermal consolidation of aluminum and copper powder. The results showed that the mechanical properties of aluminum samples prepared by SPS were poor owing to bad consolidation condition because of the complete oxide film of aluminum particle powder having strong binding energy with oxygen, while the mechanical properties of copper samples prepared by SPS were good due to excellent consolidation condition because of the oxide film dissolution in thermal mechanical consolidation. In order to solve the poor consolidation condition owing to oxide film, the effect of the different treatments on oxide film and consolidation condition was investigated by posttreatment process(extrusion), pretreatment process(high energy ball milling), and pre and post treatment process respectively.Finally, this chapter had discussed the effect of temperature on the consolidation condition, microstructure and mechanical properties of powder compact extruding aluminum. The results showed that the higher the extrusion temperature, the better consolidation condition and the more serious damage of the oxide films. The grain size, tensile strength, and fracture elongation were increased with the increase of temperature.