Cavitation- corrosion known as a destroyer factor in equipment like pumps, valves, impellers etc. .This phenomenon that occurs in corrosive solution, related to the formation and explosion of bubbles that creates by fluctuations of pressure inside the liquid. Among engineering materials, aluminum bronzes and especially nickel- aluminum bronze (NAB), for having suitable corrosion and mechanical properties employing in this situations. Improving mechanical behavior with preservation or enhance corrosion resistance of this alloys, is a principal key for developing of aluminum bronzes in cavitation environments. Micro- alloying of the materials and Cu alloys with boron indicates that this element can has beneficial results in grain refining, grain boundary strengthening and improving mechanical properties. As yet, do not study is on doping boron in Al- bronzes and effects of this on corrosion and cavitation- corrosion. Study of this issue can predispose for betterment of cavitation- corrosion resistance of this alloys. In this research, with aid of direct melt reaction method, micro- alloyed Al- bronzes produced and effect of boron on corrosion behavior of samples with static corrosion and cyclic polarization tests examined, and cavitation- corrosion of samples with rotating disk rig was studied. Evaluation of cavitation resistance of materials with rotating disk rig is beneficial in specification of initiation of cavitation attack. Also, for surveying effect of Fe on protection film properties in cavitation- corrosion manner, used in-place injection treatment of Fe ions in test environments. Microstructure analysis indicates that boron can refine macrostructure of Al- bronze castings. Results of corrosion tests shown that however addition of boron in Al- bronzes increases corrosion resistance via reducing corrosion current density and acceleration of passivation of this alloys, but because of creating non- uniformity on film, accelerates sensitivity of pitting. Addition of boron in Al- bronzes improved the mechanical behavior, but acceleration of pitting leaded to increase of corrosion contribution in cavitation- corrosion process that threatens the cavitation resistance. Results shown that if corrosion resistance of alloy increased (in this study with increasing Al) the negative effects of boron on corrosion properties of this alloys can reduced. With injection treatment of Fe ions in solution, a layer containing Fe creates on surface of Al- bronze that reduced effectively weight loss of materials during cavitation- corrosion. Moreover, the adherence of layer related to the percent of Al and B; and B has essentially role in this sketch. Ni- Al bronze components and especially heavy casting components like impellers of ships, for tendency of absorption of gas during casting process, always attend with defects like porosity and oxides. In this research, the effect of casting defects on cavitation- corrosion resistance of NAB studied and observed that defects leaded to removing corrosion products in environs of them in cavitation- corrosion manner. Moreover, microstructure results with electron microscopy indicates that areas between ? ? and ? ? in NAB is tender to start rupture in cavitation- corrosion process. Keywords: cavitation, cavitation- corrosion, aluminum bronze, boron, nickel- aluminum bronze.
