Research On Process And Performance Of High Intensity Cu-Ni-Sn Alloy Prepared By Powder Metallurgy

Cu-Ni-Sn alloy has been caused more and more attention due to its high strength, good mouldability, excellent anti-friction and resistant to corrosion. Cu-15Ni-8Sn with high content of Sn have the most remarkable aging deposition strengthening effect, also by this, the segregation of Sn appeared easily in traditional casting method because of the cooling speed is too slow. As a result, the ageing strengthening effect was serious reduced and the mechanical properties of the alloy.In order to solve this problem, two different methods (dumped belt rapid solidification and salt-water cooling copper-mould casting) were chosen to prepare Cu-15Ni-8Sn alloy, aiming to control the the segregation of Sn by speeding up cooling. The as-prepared alloy was crushed to obtain the pre-alloyed powder, which was used as raw material to produce the target alloy by metallurgical hot pressing sintering method. Optimization of heat treatment technology such as solid solution, deformation, and aging et al and adjustment of the type and amount of the4th elements play a significant part in inhibiting the grain growth and discontinuous precipitation, which is benefit for getting a distinct aging strengthening Cu-15Ni-8Sn alloy with uniform organization and components.The relationship between composition, organization and mechanical property has been investigated by energy spectrometer microstructure (eds), scanning electron microscopy (sem), and metallographic microscopy, rockwell hardness, shear strength, the micro attrition rate, and other test methods, which suggest:The denser alloy organization has been obtained by using the mashing pre-alloy powder as raw materials and casting with steel-mould under the condition of salt-water. It is suggest by the orthogonal test of hot-pressed sintering that temperature is the most important factor of sintering properties, and the optimized sintering process is850℃×150s. The organization and proterty variation of powder metallurgy samples prepared by Cu-15Ni-8Sn with the solution temperature, cold deformation, aging temperature and aging time has been systenatic investigated. Primary and secondary factors were obtained according to the orthogonal experiment results:deformation volume>ageing time>ageing temperature>solution temperature. And the optimum technology route were also achieved:840℃×15min solution+40%cold deformation+400℃×4h aging. In this case, the Cu-15Ni-8Sn alloy showed high hardness (37.6HRC) and considerable shear strength (570.76MPa) synchronously. The peak surface hardness and shear strength of Cu-15Ni-8Sn improved13.8%and7.3%at the Nb content of1.5%compared with original alloy because that the Nb is benefit for refining alloy grain and delaying discontinuous precipitation, speeding up the aging process which is conducive to the improvement of the mechanical behavior Cu-15Ni-8Sn alloy.