Applications of Ni_3 (Si, Ti) Based Intermetallic Compounds to Chemical Parts, Heat Resistance and Wear Resistance Materials

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1) Development of intermetallic compounds showing superior corrosion resistance and ductilityIt was found that Ni_3 (Si, Ti) alloys with Cu (0.5-3at%), Ta (1-4at%) and boron (0.001-0.01wt%) showed superior sulfuric acid resistance and good ductility than those in Hastelloy D or Inconel 50.2) Development of intermetallic compounds showing superior creep resistanceIt was shown that Ni-Ti (7-11at%) -Si (5-12) -Co (1-30) alloys along pseudo-binary Ni_3 (Si, Ti) -Co_3 (Si, Ti) had more excellent creep strength than Inconel 718.3) Development of well-castable intermetallic compoundsWell-castable Ni_3 (Si, Ti) based intermetallic compounds with better corrosion resistance, machinability and polishability were developed and they were shown to be applicable to the watch case or the precession parts.4) Development of intermetallic compounds showing the superplasticityNi_3 (Si, Ti) alloys with and without boron were shown to display the superplastic deformation at 1073K-1173K at the strain rates below 5x10^<-4>/s. This result indicates that this alloy can be formed easily and the superior mechanical properties can be obtained.5) Scale up and working as actual partsLarge size ingots (>2kg) were made in Argon gas by the induction furnace using alumina crucible and then machined to the parts which were utilized as some parts in high temperature mechanical testing machine. Performance was reliable and excellent, and also the degradation was minimal.6) Interpretation of bonding between constituent and doping elementsStrongly directional bonding between constituent element Ni and boron atom were shown by NMR measurement. Also, the site of boron atoms was determined.7) Systematic observation for the peculiar strength behavior of Ni_3 (Si, Ti) alloysThe strength anomaly in Ni_3Si and Ni_3 (Si, Ti) alloys was interpreted based on the TEM observation for the deformed dislocation microstructures.