Effect of Cyclic Stressing on Various Properties of Electroless Deposited Ni-P Alloys

The microstructure of electroless deposited Ni-P alloys in the composition ranging from 5.3 to 7.9 mass%P has been studied by a large angle X-ray scattering method. The changes of microstructure and mechanical properties by cyclic stressing at various stress levels were examined by a X-ray scattering technique and also by a static bend test.The results obtained are as follows;(1) The microstructure of electroless Ni-P alloys containing less than about 7 mass%P is a supersaturated solid solution of fcc Ni in which an excess of P dissolves. On the other hand, the electroless Ni-P alloys containing more than about 7 mass%P are completely amorphous structure. This structure is quite similar to that of the amorphous alloys obtained by other methods such as rapid quenching and electrodeposition.(2) The amorphous Ni-P alloys prepared by the present method have some excellent properties such as good ductility and high corrosion resistance. But, these excellent properties deteriorate by cyclic stressing, particularly by tensile stressing, because of a changes in amorphous structure due to structural relaxation and local crystallization.