Fracture strength metals

The fracture strengths of polymers are generally lower than those of metals and ceramics. The mode of failure for thermosets is generally referred to as the materials being brittle. Cracks, related to bond breakage, occur at points of excess stress. These create weak spots and may lead to fracture if the applied stress, appropriate to create bond breakage, continues. 

As was the case for metals, poly crystalline ceramics show a dependence of mechanical properties on grain size, as given earlier by the Hall-Petch relation in Eq. (5.22), which in this case applies to fracture strength, ay ... 

Fig. l-(b) shows a stress-strain curve for a brittle material such as non-metallic material, (the material that does not conduct electric current), or an intermetallic compound, such as TiFe for which failure occurs before any appreciable plastic deformation. Thus, there is no yield stress or plastic deformation. The fracture strength is essentially at the elastic limit or the yield stress. 

In early nanocomposites, hard and strong dispersoids, such as SiC, Si3N4, TiC, etc., were mainly incorporated into the matrix to improve the mechanical properties. But in later years, enhancement of fracture strength was also achieved by addition of even soft and weak dispersoids like metals, graphite and h-BN [3-5], The density, microstructure and mechanical properties of nano-sized particulate dispersion nanocomposites were strongly dependent on the volume fraction of particulate dispersion and sintering conditions. 

Some reports have cited bridging across the relatively ductile metal particles as mechanisms which contribute to the increase in fracture strength.54 Other reports demonstrate cracks propagating at the metal-ceramic interfaces,... 

W. Brown, J. Srouli, Testing of high-strength metallic materials for viscosity of fracture under plane deformation, Mir, Moscow (1972). 

Exposure to moisture at a temperature in the 200-300 C range tends to enhance the tetragonal to monoclinic transition which is detrimental to the mechanical strength of a zirconia membrane. This effect of water promoting phase transition at a lower temperature is common among metal oxides. Therefore, such long-term exposure tends to cause a drastic reduction in fracture strength [Stevens, 1986]. 

Recently, a modified small punch testing (MSP) method has been developed for mechanical evaluation of ceramic and ceramic/metal composite materials used in FGMs [5]. In the present study, the MSP method was applied to evaluate TiC-based ceramics, which are employed as ceramic-side materials in a TiC/Ni3Al FGM. Because the TiC/Ni3Al FGMs apparently show different damage behavior at temperatures from 1208 to 1373 K, the fracture strength and deformation of TiC-based ceramics were measured at these two critical temperatures. The differences in the behaviors of different TiC sintered bodies and their... 

ASTM D34.3.3. 1993, Fracture strength in cleavage of adhesives in bonded metal joints. 

V.S. Ivanova, Synergetics. Strength and Fracture of Metallic Materials, Cambridge International Science, Cambridge, UK, 1988. 

First Report of Special ASTM Committee on Fracture Testing of High-Strength Metallic Materials, ASTM Bull. (Jan., Feb. 1960). 

TMFG transition metal fluoride glasses (Tp fracture strength... 

The fracture strength of the butt joint welded by the high-current GMA welding process was studied at room and low temperatures using a deep-notch test specimen, 400 mm wide. The edge notches of the specimens were located in the weld metal or along the bond. The test results are shown in Fig. 5. For comparison, the relationship between the fracture strength and the temperature of the base metal is shown with a dashed line. 

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