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- Larker, Rickard, et al.
(författare)
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Diffusion bonding of CMSX-4 to UDIMET 720 using PVD-coated interfaces and HIP
- 1999
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Ingår i: Journal of engineering for gas turbines and power. - : ASME International. - 0742-4795 .- 1528-8919. ; 121:3, s. 489-493
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing interest in development of manufacturing methods for Dual Property BLISKs, consisting of creep resistant airfoils and fatigue resistant disks bonded together by a durable joint. Optimum heat treatments are, however, very different for creep resistant single crystal CMSX-4 and fatigue resistant polycrystalline Udimet 720 selected in this study, but fortunately the first aging treatment for CMSX-4 (1140°C, 2-6 h, AC) is similar to the partial solution treatment of U 720 HS2 (1115°C, 4 h, OQ). Based on this, diffusion bonding was performed by HIP at 1120°C and 200 MPa argon pressure for 4 h, followed by cooling to 400°C. Subsequently, a shortened Udimet 720 HS2 two-step aging treatment was adopted by heating to 650°C for 6 h followed by cooling to 400°C, heating to 760°C for 2 h, and finally cooling to R.T. under remaining HIP pressure. Plasma etching followed by thin (80 nm) PVD coating with either nickel or titanium were used to clean and protect the polished surfaces before joining. The selection of coatings was governed by the possibility to reduce oxidized nickel by flushing with hydrogen at 330°C during evacuation of the HIP capsules, and by the large solubility of oxygen in titanium. Hot tensile testing was performed at 750°C on both joined and reference materials subjected to the modified heat treatment. Initially solution treated Udimet 720 and CMSX-4 comprised the reference materials. The testing showed that joints with Ni-PVD coatings were almost as strong as Udimet 720 (although with very limited elongation), while the joints with Ti-PVD coatings were weaker.
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| 2. |
- Rodriguez, M, et al.
(författare)
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CT in malignancy grading and prognostic prediction of non-Hodgkin's lymphoma
- 1999
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Ingår i: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 40:2, s. 191-197
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The presence of tumor inhomogeneities in MR images of non-Hodgkin's lymphoma (NHL) provides information about malignancy grade and prognosis. The aim of this study was to determine whether CT images are also informative in these respects. MATERIAL AND METHODS: Sixty-three CT examinations in patients with NHL (32 high-grade and 31 low-grade tumors) were reviewed retrospectively by two senior radiologists. The tumor patterns were classified subjectively as homogeneous, slightly inhomogeneous or severely inhomogeneous and their relations to malignancy grade, clinical characteristics and prognosis were determined. RESULTS: Sixteen out of 17 patients with a severely inhomogeneous tumor pattern had high-grade NHL tumors while 21 out of 29 patients with a homogeneous tumor appearance had low-grade NHL tumors. Among chemotherapy-treated patients, those with the highest degree of inhomogeneity had a significantly worse prognosis (9 out of 11 patients died). This relationship was not found in patients treated with radiotherapy. CONCLUSION: A severely inhomogeneous tumor pattern on CT images was found to be associated with a high malignancy grade in NHL. This CT pattern was also compatible with a poor prognosis in patients treated with chemotherapy.
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