On Electrolyte To Separate Non-metallic Inclusions In Ni-base Alloys With Electrolytic Extraction Method

With the rapid development of aviation, aerospace, missile and electronic industrial technology, the requirements for Ni-based alloys are stricter, especially for thin wires. Not only chemical constitution and service performance are limited, but also inner and surface qualities are required.The quality of Ni-based alloy wires produced by one alloy company is examined and it is found that brittle nonmetal inclusions are the main cause of crack and break in products. Because the inclusions not distributed uniformly in alloy base, it is very difficult to find all the inclusions on the surface of the sample. And from the sample, only a face with inclusions can be observed. Its three dimensional state cannot be observed. So judging the inclusions' essential performance exactly is very difficult.As there are only a few researchers who studied the non-metallic inclusions in nickel-base alloy, we developed a new kind of electrolyte applied for nickel-base alloy. New neutral electrolyte is made up by mixing oxysalt, sodium chloride and citric acid, etc. New electrolyte can not only effectively extract nonmetal inclusions in Ni-based alloys but also can have other good characters, such as, temperature and pH value is invariable during electroanalysis, anode mud precipitation of garrulous shape is little, electroanalysis process is calm; garrulous precipitation mixed in inclusions in half transparent film is so little that can be easily cleaned & separated, and high harvest rate is acquired. The inclusions extracted keep their former morphologies well in alloy, thus improving the veracity of experiment.In addition, the separated inclusions is studied in this thesis. Silicate, aluminate and their composite inclusions are composed of elements such as Al, Si, Ca, Mn, Mg, Ti, Fe, Ni and so on. These inclusions exhibit many shapes such as sphericity,tablet,strip and abnormal shape because of different inborn time,solidified condition and component.In these kinds of Ni-based alloys, big brittle macroscopic inclusions have the huge impact on the properties of alloys, especially the composite inclusions composed of Ti,Al,Fe in 4J43 alloy and Cr20Ni80 alloy. This kind of impurity is mainly titanic oxides or nitrides generated by oxidizing of titanium in smelting which exhibits abnormal acute angle with size of 20-300μm and higher rigidity, belonging to brittle impurity with low strain rate. In the three alloys, the size of inclusions in the N6 alloy is smaller. The largest impurity is less than 50μm.