Techniques for Mechanical and Thermal Testing of Ti3Al/SCS-6 Metal Matrix Composites

Hartman, G. A.; Russ, Stephan M.

doi:10.1520/stp22848s

Cited by 27 publications

(6 citation statements)

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“…Unnotched tension tests were conducted using an automated, servo-controlled, hydraulic, horizontal test system. 13,14 The tests were conducted under load-line displacement control at a rate (␦ . ) of 0.05 mm/s.…”

Section: (1) Test Proceduresmentioning

confidence: 99%

“…2 Notched fracture tests were conducted using an automated, servo-controlled, hydraulic, horizontal test system. 13,14 The single edge notched specimen geometry with clamped ends, MSE(T) 15 shown in Fig. 2, was used for all of the tests.…”

Section: (1) Test Proceduresmentioning

confidence: 99%

“…Further details of the test equipment have been described elsewhere. 13,14 Various methods of thermocouple attachment were investigated. The method which produced the most repeatable temperature measurements with minimal damage to the specimen surface was chosen for use in testing.…”

Section: (2) Elevated-temperature Testingmentioning

confidence: 99%

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Notched Fracture Behavior of an Oxide/Oxide Ceramic‐Matrix Composite

Kramb

John

Zawada

1999

Journal of the American Ceramic Society

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The fracture behavior of an oxide/oxide ceramic-matrix composite, alumina/alumina-silica (Nextel610/AS), was investigated at 23°and 950°C using a single edge notched specimen geometry with clamped ends. Crack growth and damage progression were monitored during the tests using optical microscopy, ultrasonic C-scans, and crack mouth opening displacement. The net section strength of Nextel610/AS was less than the unnotched ultimate tensile strength. The failure mode was nonbrittle with considerable nonlinear deformation prior to and after the peak load at 23°and 950°C. The effect of temperature on the notched strength was significant. Net section failure stress decreased 50% when temperature was increased from 23°to 950°C. Observations of damage progression indicated that the reduction in notch strength with temperature was associated with self-similar crack growth at 950°C. Ultrasonic C-scans were found to be an effective method of monitoring damage progression. Ultrasonic attenuation ahead of the notch tip was correlated with surface matrix cracks and exposed fiber lengths on the fracture surface.

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Section: (1) Test Proceduresmentioning

confidence: 99%

Section: (1) Test Proceduresmentioning

confidence: 99%

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Notched Fracture Behavior of an Oxide/Oxide Ceramic‐Matrix Composite

Kramb

John

Zawada

1999

Journal of the American Ceramic Society

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“…31) Prior to testing, the samples were electrodischarge machine (EDM) cut into a dogbone geometry, typically containing a gage length of 25 mm and a gage width of 13 mm, and the EDM recast layers were removed through silicon carbide paper grinding to a 600-grit finish. Strain was measured during the tensile tests with an alumina-arm extensometer attached directly to the gage section of the sample.…”

Section: Tensile Experimentsmentioning

confidence: 99%

The Elevated-Temperature Creep Behavior of Boron-Modified Ti-6Al-4V Alloys

Boehlert

Chen

2009

Mater. Trans.

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This work investigated the effect of nominal boron (B) additions of 0.1 mass% and 1 mass% on the elevated-temperature (673-728 K) tensile-creep deformation behavior of a Ti-6Al-4V(mass%) alloy for applied stresses between 400-600 MPa. The alloys were evaluated in the as-cast and cast-then-extruded conditions. Boron additions resulted in a dramatic refinement of the as-cast grain size and TiB whisker volume percents of approximately 0.6 and 6.0 for the Ti-6Al-4V-0.1B and Ti-6Al-4V-1B alloys, respectively. The extrusions were performed in thephase field and resulted in the TiB-phase whiskers aligning in the extrusion direction. The creep resistance of the as-cast alloys significantly improved with increased B concentration, where around an order of magnitude decrease in the secondary creep rate was observed between the Ti-6Al-4V-1B and Ti-6Al-4V as-cast alloys. Grain refinement due to the B addition did not deleteriously affect the creep resistance in the temperature and stress ranges considered, where dislocation creep was suggested to be the dominant secondary-creep mechanism. The enhanced creep resistance was attributed to load sharing by the TiB whiskers. For the same nominal B contents, the cast-then-extruded alloys exhibited significantly greater creep resistance and tensile strength than the as-cast alloys. This was explained to be an effect of the -phase texture and the decreased lath spacing in the cast-then-extruded alloys compared with the as-cast alloys. The cast-then-extruded alloys exhibited four times lower lath widths than the as-cast alloys, and the -phase was strongly textured such that the basal plane was predominately oriented perpendicular to the extrusion axis. Comparing the cast-then-extruded alloys, the Ti-6Al-4V alloy exhibited the greatest creep resistance. Overall the -phase consisted of approximately 80% of the microstructure, and the -phase texture appeared to be more dominant to the creep resistance and tensile strength than the small volume percent of TiB-phase in the microstructure. Although B is not necessary to optimize the elevated-temperature creep performance of the Ti-6Al-4V alloy, when boron was present, greater boron additions increased the creep resistance. In-situ creep observations of the surface indicated that the TiB whisker cracking occurred prior to slip and void formation in the þ phases. This was followed by = interface cracking and ductile failure of the þ microstructure.

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“…The fatigue test equipment used for this study was designed to perform room and elevated temperature fatigue testing of metals and metal and ceramic matrix composites [10][11][12]. This system is unique in that it is a horizontal test frame that was specifically designed for testing of advanced composites that are fairly brittle in nature.…”

Section: Fatigue Test Equipmentmentioning

confidence: 99%