Abstract
The influence of the sub-nano Ni(3)P and Cu(3)P phases on the microstructure, mechanical properties, and strengthening mechanism of Cu-20Pb-5Sn-xP (x = 0,0.05,0.1,0.3,0.5) alloy were discussed under the addition of P to obtain a new Pb-Sn bronze alloy applying for bimetallic cylinder block. The results showed that the tensile strength and hardness of the Pb-Sn bronze alloy increase with the P contents, while the elongation increased first and then decreased. The main strengthen mechanism was that sub-nano Ni(3)P and Cu(3)P phases dispersed in the matrix, hindering the movement of dislocations during deformation. Additionally, the grain refinement also contributed to the improvement of mechanical properties. The Ni(3)P phase is easier to form than the Cu(3)P phase. And it is easier to combine with the matrix and more stable. The Ni(3)P and Cu(3)P phases were studied by using different characterization techniques, such as OM, SEM, EDS, XRD, TEM and First-principles, Phase diagram calculation method. When P is added to the alloy, the Ni(3)P phase first appears in the alloy, and when the P content increases to more than 0.3 wt%, the Cu(3)P phase begins to appear. This is because the Ni(3)P phase is easier to form than the Cu(3)P phase and is more stable. Only after part of P reacts with Ni dissolved in copper to form Ni(3)P, the remaining P and Cu can form Cu(3)P.