Effect Of Melting Process On The Microstructures And Hardnesses Of Aluminum Bronze Casting Alloys

The aluminum bronze is a new type of copper alloy, which began to study in the beginning of the twentieth century. The casting of this alloy has compact structure, and superior mechanical properties than those of brass and tin bronze. In addition, it has good corrosion resistance in the air, sea water, chloride and acid solution. Consequently, it has been widely used in machinery, metallurgy, manufacturing process, aerospace and buildings, etc.By using two kinds of different charging sequence, we prepared10-3-2aluminum bronze casting alloys, and named them sample A and sample B respectively. In addition, the Optical Microscope, Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and the X-Ray Diffractometer (XRD) were applied to reveal their microstructural details, phase composition in as-cast, and measured the microhardness of the of the two samples by the microhardness meter.The results show that, the chemical constitution and phase composition of the two samples are almost the same, though there are obvious differences in the micro structure details. In other words, the different charging sequence can significantly influence the form and distribution of the alloy organization, rather than the contents of the elements and the type of phase. The organizations of two samples are all the same, that’s to say. main phase is phase a in the matrix, where dispersive distribute martensitic phase β, phase γ2and particle pointlike phase K. Though the martensitic phase β are remarkable coarse grains in the sample B, which causes the strengthening phase of the alloy concentration distribution. The result also shows that, the microstructure of "first aluminum then copper" is finer than that of "first copper then aluminum" sequence, which has better strengthen effect. In addition, the sequence of "first aluminum then copper" plays an effective role in the actual production process.