To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The effects of boron and zirconium contents from 0 to 0.049 wt% on the casting fluidity, as-cast microstructure and mechanical properties of IN718C superalloy are systematically investigated. The results show that as the B or Zr content increases, the fluidity firstly increases and then decreases. The optimum fluidity is obtained at the pouring temperature of 1470 °C when the content of B is 0.0059 wt% or Zr is 0.042 wt%, respectively. The addition of Zr can lead to the formation of blocky laves phase, but B has no influence on microstructure morphology. Furthermore, the addition of B or Zr can effectively improve the tensile and stress life properties as well as casting fluidity of IN718C superalloy. As compared with IN718C master alloys, the tensile strength can increase 6.2–8.6% and stress life can be improved by 1.3 times when B content is 0.0059 wt%. In addition, when the alloy contains 0.042 wt% Zr, the tensile strength can increase 5.6–7% and stress life can increase 1.076 times than that of the master alloy.
The effects of W, Re, Cr, and Mo on microstructural stability, such as the morphology of γ′ phase and the topologically close-packed (TCP) phase precipitation are systematically investigated in eleven kinds of Ni-based single crystal superalloys containing certain amounts of Co, Al, and Ta. After heat treatment, all the designed alloys show different sizes of γ′ phases with typical cuboidal morphology occupying 75% of the total volume. With increasing Re content, the size of γ′ decreases obviously, while the size of γ′ decreases slightly with increasing Cr and Mo contents. Increasing W does not affect the size of γ′. As a result of thermal exposure at 1000 °C for 1000 h, some acicular, rod-like, and blocky TCP phases are precipitated in most alloys. It is noted that Mo and Re can strongly promote the precipitation of TCP phase, but W has no obvious effect on TCP phase precipitation. In addition, transmission electron microscope analysis indicates that these TCP phases are σ phase, μ phase, and R phase.
The effect of Co on element segregation and microstructure is investigated in the third generation Ni-based single crystal superalloys with 4, 8.5, and 11.5 wt% Co addition. The results show that the increase of Co content leads to a severe element segregation in as-cast microstructure. After heat treatment, the size of γ′ phase is slightly reduced with Co content increase. During the thermal exposure, the γ′ phase coarsens gradually but its coarsening rate decreases with increasing Co content. In addition, some acicular and blocky topologically close-packed (TCP) phases are precipitated in 4% Co and 8.5% Co alloys. However, no TCP phase can be found in 11.5% Co alloy. Finally, it may be concluded that although a higher Co content is harmful for the element segregation, it is beneficial to maintain the cuboidal morphology of γ′ phase, decrease its coarsening rate, and impede the precipitation of TCP phase.
Email your librarian or administrator to recommend adding this to your organisation's collection.