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 here? Strain, 5 1 20 586 MPa 40 60 80 Time, h 538 MPa 100 120 145 Ess = AGb kT ADGb b KT d р -Do exp(-Qc/RT) n G'))" Precision with logs, exponentials, etc.

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 here? Strain, 5 1 20 586 MPa 40 60 80 Time, h 538 MPa 100 120 145 Ess = AGb kT ADGb b KT d р -Do exp(-Qc/RT) n G'))" Precision with logs, exponentials, etc.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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