Tensile Properties to 650 ̊C and Deformation Structures in a Precipitation-strengthened Titanium-aluminum AlloyAppreciable strength levels were retained to 650 C in a Ti-10Al-1Si alloy aged in the (alpha alpha sub 2) phase field to yield optimum room temperature strength and ductility. The aging treatment precipitated a uniform distribution of alpha sub 2-particles such that, at room temperature, dislocations bypassed instead of shearing the particles at low strains. Specimens fractured at room temperature exhibited fine uniform dimples even for those aging conditions that imparted no macroscopic ductility. The main crack appeared to propagate through the planar slip bands that had cut through the alpha sub 2-particles. A two-step aging process produced a higher volume fraction of bimodally distributed alpha sub 2-particles that led to higher strength levels at elevated temperatures. Both for the single size and the bimodal alpha sub 2-particle distributions, elevated-temperature deformation structures consisted mainly of planar slip bands that sheared through the alpha sub 2-particles. |
Common terms and phrases
0.2-Percent yield strength 4.5 percent elongation a-matrix a₂-phase precipitate aging temperature aging treatment 925 Aluminum basal slip bands brittle specimens bypass mechanism bypassed the particles C/100 hours followed containing a bimodal crosshead crosshead speed deformation structure deformed at room dimple dislocation loops dislocations bypassed ductile specimens electron micrograph elevated temperatures Elevated-temperature tensile elongation to fracture followed by water fracture mode fracture surface grain boundaries high strength high volume fraction interparticle spacing large a₂-particles Lütjering Magnification MAMP phase boundary phase diagram planar slip bands precipitate particles precipitation strengthening result revealed room-temperature strength room-temperature tensile properties second aging secondary cracking sheared the a₂-particles shown in figure single-size solid solution strengthening specimens containing specimens deformed specimens fractured strength and ductility strength levels Tensile Behavior tensile ductility tensile tests Testing temperature titanium alloys transcrystalline transmission electron microscopy treatment of 925 Ultimate tensile strength uniform distribution water quench Wright-Patterson AFB zone normal 1010