| WCp/Al composite is a kind of new metal matrix composite(MMC). The WCp/Al composite has excellent radiation shielding effects because of the high atomic number of W in WC. WCp/Al composite has a good application prospect in many fields, such as aerospace industry, nuclear industry and other industries because of its advantages such as light weight, good mechanical properties and excellent radiation shielding effects. In most of the cases, the particle-reinforced composite needs to be processed by means of machining and welding in order to be used in structures. However, usually the particle-reinforced composite is hard to be processed by means of welding, which poses difficulties for the widely use of it.In this paper, aluminum matrix compounds layer was fabricated by laser deposition, which was carried out through coaxial ceramic powder feeding and wire feeding simutanously. This method reduced the process of machining. Alloying elements Ti was added into WCp/Al composite to inhibit the formation of Al4C3 phase. The influence of laser power, scan speed, wire feed speed, the proportion of WC particles and Ti powder and other parameters on WCp/Al composite was studied. The results showed that the more element Ti, the fully Al-Ti phase grew. With too much Ti, cracks even appeared in the WCp/Al composite.XRD, SEM, EDS, TEM were conducted to analysis the microstructure of the WCp/Al composite. When WC particle was added independently, WC particles were dissolved into aluminum matrix, which contributed to the formation of white column Al4 W and needle-shaped Al4 W. The Al4C3 was easy to be hydrolyzed in the humid environment, which was harmful to the properties of WCp/Al composite. When WC particle and Ti powder were added into the composite simultaneously, Al3 Ti, Al4 W, Al12 W were observed in aluminum matrix without Al4C3. All of them were granular(~10um) and dispersed in aluminum matrix.Alloying element Ti was found concentrated around WC particles. There were a lot of Ti around WC particles, mainly Al Ti3 and Ti C, decreased the spread of W and C from WC. Therefore it did not provide enough C and W for Al4 W and Al4C3. The inhibition of alloying element Ti was studied by means of thermodynamics analysis. The result showed that the standard Gibbs free energy of Ti C was far less than that of Al4C3 when the temperature was above 1450 K. The less the standard free energy change of formation, the more stable the carbide is. Ti is a very strong carbide former compared with Al4C3.The Young’s modulus of Al3 Ti was 209.8 GPa measured by Nano Indenter and the hardness of Al3 Ti was 8.9 GPa, which showed that Al3 Ti was the most considerable reinforcing phase for WCp/Al composite. The fracture behavior of WCp/Al composite was analyzed by In situ tensile technology. The result showed that micro cracks formed mainly inside WC particles and the region of Al-Ti reunion. Because Al matrix had good ductility, elastic deformation occurred to prevent the spread of cracks when tips of cracks expanded to Al matrix. When the cracks spread around the position where number of WC particles was high, the direction cracks was changed by WC particles. |
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