Foundations of Materials Science and Engineering
6th Edition
ISBN: 9781259696558
Author: SMITH
Publisher: MCG
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Chapter 6.13, Problem 62AAP
To determine
Activation energy in
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13.8 - Howson et al.studied the creep and stress-rupture response of oxidedispersion-strengthened (ODS) superalloys
produced by mechanical alloying. They determined that the activation energy for creep Qc was 619 kJ/mol by conducting
tests at a constant applied stress of 558.7 MPa at the three temperatures of 746, 760, and 774 °C.
(a) The results shown in Figure Ex13.8 were found for experimental alloy MA6000 E at 760 °C. Estimate the value of n, and
discuss this value in terms of the microstructure exhibited by the alloy (made by means of dispersion-strengthening by inert
yttrium oxide dispersoids plus precipitation-strengthening by gamma prime).
(b) By applying Equation 13.4, show how the activation energy can be found. Make the appropriate plot, and find the minimum
creep rate at the aforementioned three temperatures. Note that the activation energy is given per mole.
1) Where in the book/slides is this covered? = page # or slide session/number
2) What equations and concepts apply…
The yield point for a brass alloy that has an average grain diameter of 50 micrometers is 120 MPa.
Question-6. For solidification of a piece of FCC-metal at 860 °C. The melting point of the metal
is 1260 °C. The latent heat of fusion and surface free energy are -2.16 x108 J/m³ and 0.126 J/m²,
respectively. If nucleation is homogeneous, answer the following questions:
(a) Compute the critical radius r* in nm
(b) Compute the activation free energy AG* in J
(c) If the lattice parameter is 0.26 nm at the melting temperature, compute the number of atoms
found in a nucleus of critical size
(d) Compute the critical radius at the supercooling degree of 260 K.
Chapter 6 Solutions
Foundations of Materials Science and Engineering
Ch. 6.13 - (a) How are metal alloys made by the casting...Ch. 6.13 - Why are cast metal sheet ingots hot-rolled first...Ch. 6.13 - What type of heat treatment is given to the rolled...Ch. 6.13 - Describe and illustrate the following types of...Ch. 6.13 - Describe the forging process. What is the...Ch. 6.13 - What is the difference between open-die and...Ch. 6.13 - Describe the wire-drawing process. Why is it...Ch. 6.13 - Distinguish between elastic and plastic...Ch. 6.13 - Define (a) engineering stress and strain and (b)...Ch. 6.13 - Define (a) modulus of elasticity, (b) yield...
Ch. 6.13 - (a) Define the hardness of a metal. (b) How is the...Ch. 6.13 - What types of indenters are used in (a) the...Ch. 6.13 - What are slipbands and slip lines? What causes the...Ch. 6.13 - Describe the slip mechanism that enables a metal...Ch. 6.13 - (a) Why does slip in metals usually take place on...Ch. 6.13 - Prob. 16KCPCh. 6.13 - What other types of slip planes are important...Ch. 6.13 - Define the critical resolved shear stress for a...Ch. 6.13 - Describe the deformation twinning process that...Ch. 6.13 - What is the difference between the slip and...Ch. 6.13 - Prob. 21KCPCh. 6.13 - Prob. 22KCPCh. 6.13 - What experimental evidence shows that grain...Ch. 6.13 - (a) Describe the grain shape changes that occur...Ch. 6.13 - How is the ductility of a metal normally affected...Ch. 6.13 - (a) What is solid-solution strengthening? Describe...Ch. 6.13 - What are the three main metallurgical stages that...Ch. 6.13 - Describe the microstructure of a heavily...Ch. 6.13 - Describe what occurs microscopically when a...Ch. 6.13 - When a cold-worked metal is heated into the...Ch. 6.13 - Describe what occurs microscopically when a...Ch. 6.13 - When a cold-worked metal is heated into the...Ch. 6.13 - Prob. 33KCPCh. 6.13 - Prob. 34KCPCh. 6.13 - Prob. 35KCPCh. 6.13 - Prob. 36KCPCh. 6.13 - Prob. 37KCPCh. 6.13 - Why are nanocrystalline materials stronger? Answer...Ch. 6.13 - A 70% Cu30% Zn brass sheet is 0.0955 cm thick and...Ch. 6.13 - A sheet of aluminum alloy is cold-rolled 30% to a...Ch. 6.13 - Calculate the percent cold reduction when an...Ch. 6.13 - Prob. 42AAPCh. 6.13 - What is the relationship between engineering...Ch. 6.13 - A tensile specimen of cartridge brass sheet has a...Ch. 6.13 - A 0.505-in.-diameter rod of an aluminum alloy is...Ch. 6.13 - In Figure 6.23, estimate the toughness of SAE 1340...Ch. 6.13 - The following engineering stress-strain data were...Ch. 6.13 - Prob. 49AAPCh. 6.13 - A 0.505-in.-diameter aluminum alloy test bar is...Ch. 6.13 - A 20-cm-long rod with a diameter of 0.250 cm is...Ch. 6.13 - Prob. 52AAPCh. 6.13 - Prob. 53AAPCh. 6.13 - Prob. 54AAPCh. 6.13 - Prob. 55AAPCh. 6.13 - Prob. 56AAPCh. 6.13 - A specimen of commercially pure titanium has a...Ch. 6.13 - Prob. 58AAPCh. 6.13 - Prob. 59AAPCh. 6.13 - Prob. 60AAPCh. 6.13 - Prob. 61AAPCh. 6.13 - Prob. 62AAPCh. 6.13 - Prob. 63AAPCh. 6.13 - Prob. 64AAPCh. 6.13 - Prob. 65SEPCh. 6.13 - Prob. 66SEPCh. 6.13 - A 20-mm-diameter, 350-mm-long rod made of an...Ch. 6.13 - Prob. 68SEPCh. 6.13 - Prob. 69SEPCh. 6.13 - Consider casting a cube and a sphere on the same...Ch. 6.13 - When manufacturing complex shapes using cold...Ch. 6.13 - Prob. 74SEPCh. 6.13 - Draw a generic engineering stress-strain diagram...Ch. 6.13 - (a) Draw a generic engineering stress-strain...Ch. 6.13 - Prob. 77SEPCh. 6.13 - Prob. 78SEPCh. 6.13 - Prob. 79SEPCh. 6.13 - The material for a rod of cross-sectional area...Ch. 6.13 - What do E, G, v, Ur, and toughness tell you about...Ch. 6.13 - A cylindrical component is loaded in tension until...Ch. 6.13 - Referring to Figures 6.20 and 6.21 (read the...Ch. 6.13 - (a) Show, using the definition of the Poissons...Ch. 6.13 - A one-inch cube of tempered stainless steel (alloy...Ch. 6.13 - Prob. 87SEPCh. 6.13 - Prob. 88SEPCh. 6.13 - Prob. 89SEPCh. 6.13 - Prob. 90SEPCh. 6.13 - Prob. 91SEPCh. 6.13 - Prob. 92SEPCh. 6.13 - Prob. 93SEPCh. 6.13 - Prob. 94SEPCh. 6.13 - Starting with a 2-in.-diameter rod of brass, we...Ch. 6.13 - Prob. 96SEPCh. 6.13 - Prob. 97SEPCh. 6.13 - Prob. 98SEPCh. 6.13 - The cupro-nickel substitutional solid solution...Ch. 6.13 - Prob. 100SEP
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- Excellent combinations of hardness, streneth, and toughness are obtained from bainite. One heat treater austenitized a eutectoid steel at 750°C, quenched and haid the steal at 250°C for 15 min, and finaly permitted the staal to cool to room temperature. Did he produce the required bainitic structure? Use the diegram below in your answer Answer: Tie ReckvellChndrearrow_forwardA sheet of a 70% Cu-30% Zn alloy is cold-rolled 20% to a thickness of 3.0mm. The sheet is then further coldrolledto 2.0 mm. What is the percentage cold work?arrow_forwardCurrent Attempt in Progress (a) Estimate the activation energy for creep (i.e., Qc in Equation 8.22) for the S-590 alloy having the steady-state creep behavior shown in animated Figure 8.33. Use data taken at a stress level of 300 MPa (43,500 psi) and temperatures of 650°C and 730°C. Assume that the stress exponent n is independent of temperature. (b) Estimate ė, at 600°C (873 K) and 300 MPa. Part 1 Excellent! What is Qc in J/mol? Qc = 480000 J/molarrow_forward
- (b) For the same bar, if the engineering strains are 0.05 and 0.10 at engineering stresses of 200 and 220 MPa respectively, what would be the work hardening exponent of pure aluminium?arrow_forwardHigh Strength Microalloyed Steels for Petroleum Pipelines : At present, due to worldwide increased demand for oil, there is a need to develop exceptionally strong (yield strength of @800 MPa) steels for pipelines. Such strong steels allow for operating the pipelines under higher pressures and over a long distance. Such microalloyed steels often can contain such elements as Mn, Nb, V, Ti, Mo, Ni, Cr, and Cu. (a) What other factors must be considered for high-strength steels for oil pipelines? (b) Based on what you have learned in terms of mechanisms of strengthening, how can you choose the best possible alloying elements for this application? Assume that you can conduct whatever experiments are necessary.arrow_forwardA nitriding heat treatment of a BCC steel normally requires 2 h at 600 °C. What temperature would be required to reduce the heat treatment time to 1 h?(Q =76570 J/mol, Do =0.0047x10- 4 m2/s)arrow_forward
- How much time (in seconds) is required for austenite to transform to 50% bainite at 300°C?arrow_forwardThe minimum yield strength for iron with an average grain size of 6x10^-2 mm is 135 MPa, this increases to 260 MPa when the average grain size is reduced to 8x10^-3 mm.What must the average grain size be to achieve a yield strength of 205 MPa.arrow_forwardOrdinary sheets of borosilicate glass are tested in bending, and are found to fracture at an average stress of 72 MPa. After thermal tempering, the stress at failure increases by 90%. What are the sign and magnitude of the stress induced in the glass by the tempering operation?arrow_forward
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