| 1. |
- Bengtsson, S., et al.
(författare)
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New Aluminium Alloy Tailored For Powder Bed Fusion - Laser Beam Process
- 2022
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Ingår i: World PM 2022 Congress Proceedings.
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Konferensbidrag (refereegranskat)abstract
- The powder bed fusion - laser beam (PBF-LB) process can produce parts with complex geometry. Light weight designs can be created and by using light alloys further weight savings can be achieved. However, minimizing printing defects using standard aluminium alloys, such as 2000, 6000 and 7000 series alloys, have proved to be difficult since they are all prone to solidification cracking. In the present study, two aluminium alloys are addressed: The first alloy is the AlSi10Mg alloy known for easy printing and consistent quality in PBF-LB printing process. The second material is a novel alloy from self-developed Al-Mn-Cr-Zr family of alloys designed to inherently resist solidification cracking, while also providing strong ageing response. The quality of printing and the resulting mechanical properties are compared. The results show that the new material prints in a robust way and that the mechanical properties are superior to those of AlSi10Mg.
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| 2. |
- Lazar, Isac, et al.
(författare)
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In situ imaging of precipitate formation in additively manufactured al-alloys by scanning X-ray fluorescence
- 2024
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Ingår i: European Journal of Materials. - 2688-9277. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Al-alloys incorporating Mn, Cr and Zr, tailored for powder bed fusion-laser beam processes with solubilities three times equilibrium have recently been developed that yield a high strength. Mn and Cr-enriched precipitates that form during printing and heat treatment influence the material’s mechanical properties hence making it important to understand their kinetics. In this study, direct imaging of these precipitates was accomplished through the utilisation of in situ synchrotron-based scanning X-ray fluorescence. During heat treatment, a selective accumulation of Cr and Mn in two distinct types of precipitates at grain boundaries was observed. Additionally, the microstructure at the melt-pool boundary, containing precipitates found in the as-printed state, remains thermally stable during the heat treatment. Both these results shed light on the active role Cr plays in the precipitation kinetics of the material. The study also demonstrates the significant value of employing high-sensitivity in-situ X-ray fluorescence microscopy in exploring the kinetics of sub-micrometre scale precipitation.
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| 3. |
- Lindgren, Kristina, 1989, et al.
(författare)
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Atom probe tomography characterisation of powder forged connecting rods alloyed with vanadium and copper
- 2022
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Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- The precipitation of V and Cu in the powder forged connecting rods of Fe-V-Cu-C alloy, were studied by atom probe tomography (APT). The purpose of alloying with V was to further improve the mechanical properties of the existing powder forged materials based on Fe-Cu-C. In this study, materials tested at room temperature and 120 degrees C were investigated. It was found that Cu was unevenly distributed on a micrometer scale. The local Cu content affected the Cu precipitation; a higher Cu content resulted in a higher volume fraction of precipitates. The V was found to form very small nitrides. The N presumably originates from the sintering process. The vanadium nitrides act as nucleation points for the Cu precipitates during cooling of the material during fabrication. APT analysis of the deformed material close to the fracture surface of the tensile test samples showed a similar volume fraction of Cu precipitates, but statistical analysis of the data indicates that both Cu and VN precipitates are more diffuse than in the undeformed material.
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| 4. |
- Markstrom, Andreas, et al.
(författare)
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Experimental and thermodynamic evaluation of the Co-Cr-C system
- 2022
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Ingår i: International Journal of Materials Research - Zeitschrift für Metallkunde. - : WALTER DE GRUYTER GMBH. - 1862-5282 .- 2195-8556. ; 97:9, s. 1243-1250
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Tidskriftsartikel (refereegranskat)abstract
- New experimental results on the liquid + graphite + M7C3 equilibrium are presented. The solubility of Co in the M7C3 carbide has been measured at 1523 and 1723 K. These measurements together with recently published measurements on the fcc + graphite + M7C3 equilibrium show that the solubility of Co in the M7C3 is much higher than predicted from thermodynamic calculations. A new thermodynamic description of the Co-Cr -C system is presented which accurately describes the solubility of Co in the M7C3 carbide in the temperature range 1373 - 1723 K.
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| 5. |
- Mehta, Bharat, 1993, et al.
(författare)
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Advancing novel Al-Mn-Cr-Zr based family of alloys tailored for powder bed fusion-laser beam process
- 2023
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Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 967
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing coupled with modern computational tools have enabled novel alloy design possibilities to create materials for the future. One such example is the Al-Mn-Cr-Zr based family of alloys tailored for powder bed fusion-laser beam process. This alloy system has previously been shown to produce crack free samples with good precipitation hardening response and strong thermal stability up to 523 K 2500 h. The current study investigates modifications made to enhance the mechanical response of the alloys. It was done by creating three novel alloy variants with higher Zr and addition of Mg. Interestingly, increasing Zr independently triggered grain refinement while addition of Mg independently causes significant increase in as-printed hardness albeit causing solidification cracking. Desirable properties were achieved when both higher Zr and addition of Mg was done at the same time. As-printed hardness enhanced by 30 % from previously known as-printed hardness of 102 HV to 132 HV in one of the variants. Upon direct ageing, peak hardness of 172 HV is observed thus suggesting retention of precipitation hardening.
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| 6. |
- Mehta, Bharat, 1993, et al.
(författare)
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Al–Mn–Cr–Zr-based alloys tailored for powder bed fusion-laser beam process: Alloy design, printability, resulting microstructure and alloy properties
- 2022
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Ingår i: Journal of Materials Research. - : Springer Science and Business Media LLC. - 0884-2914 .- 2044-5326. ; 37:6, s. 1256-1268
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Tidskriftsartikel (refereegranskat)abstract
- This study introduces a family of unique Al–Mn–Cr–Zr-based aluminium alloys illustrated by two ternary and one quaternary variants. The choice of alloy compositions has created a system resistant to solidification cracking while retaining high amount of solutes in solid solution in as-printed condition. Good relative density (~ 99.5%) has been demonstrated along with microstructural study supported by X-ray diffraction to display solidification structure with nanometric precipitate formation in small amounts in as-printed condition. High levels of Mn and Cr produce significant solid solution strengthening reaching hardness of up to 102 HV in as-printed condition. Additionally, the combination of Mn, Cr and Zr is shown to be important to control precipitation strengthening upon direct ageing and coarsening resistance due to slow diffusivity. To elucidate the concept of precipitation strengthening, one set of alloys was aged at 678 K between 0 and 10 h and microhardness results showed that average hardness response reached 130 HV for the quarternary alloy. Graphical abstract: [Figure not available: see fulltext.]
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| 7. |
- Mehta, Bharat, 1993, et al.
(författare)
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Effect of precipitation kinetics on microstructure and properties of novel Al-Mn-Cr-Zr based alloys developed for powder bed fusion – laser beam process
- 2022
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 920
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the precipitation kinetics and resulting effect on microstructure and property of a family of novel high strength Al-Mn-Cr-Zr alloys designed for powder bed fusion – laser beam process. The alloys have been shown to be printable without solidification cracking along with high supersaturation of solutes in as-printed state. Upon direct ageing, two families of precipitates namely Al-Mn and Al-Zr are observed. Al-Mn containing precipitates, which are observed in as-printed condition as nanometric precipitates decorating special regions are seen to grow preferentially at grain boundaries, which is followed by growth in bulk of the sample. A possible explanation is suggested to be a higher diffusivity at grain boundaries leading to faster growth while depleting solutes around grain boundary region quickly. The Al-Zr precipitation, which normally follows bulk precipitation is observed to co-precipitate with Al-Mn precipitates. Optimised heat treatments are seen to achieve peak hardness of 143 HV at 623 K for 24 h and 142 HV at 648 K for 14 h as compared to 102 HV in as-printed condition for one of the alloys. This overall hardening effect is attributed majorly to Al3Zr nanoprecipitates along with semi-coherent Al12Mn precipitates.
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| 8. |
- Mehta, Bharat, 1993, et al.
(författare)
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Thermal Stability In Al-Mn-Cr-Zr Based Aluminium Alloys Tailored For Powder Bed Fusion - Laser Beam
- 2022
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Ingår i: World PM 2022 Congress Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Al-Mn-Cr-Zr family of alloys tailored for powder bed fusion - laser beam process have been developed by the authors. The alloys were designed by leveraging negligible solidification range close to solidification, leading to an "inherently crack free" alloy system. These alloys have been designed to benefit from higher amount of solutes in solid solution, which leads to stronger precipitation hardening via direct ageing to achieve high strengths. Since the alloying elements were selected having low bulk diffusivities, slower precipitation kinetics is expected which suggests retention of high strength even after secondary ageing post peak hardening. Upon secondary ageing the alloys at 523K for 2544 hours and 623K 1054 hours negligible hardness loss at 523K and 17 HV loss at 623K was observed. This was benchmarked against Scalmalloy® which was seen to have negligible hardness loss at 523K and 28 HV loss at 623 K respectively.
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| 9. |
- Mehta, Shivam, et al.
(författare)
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Role of Cr in Mn-rich precipitates for Al–Mn–Cr–Zr-based alloys tailored for additive manufacturing
- 2024
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Ingår i: Calphad. - : Elsevier BV. - 0364-5916 .- 1873-2984. ; 84
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Tidskriftsartikel (refereegranskat)abstract
- Novel alloy concepts enabled via additive manufacturing processes have opened up the possibility of tailoring properties beyond the scope of conventional casting and powder metallurgy processes. The authors have previously presented a novel Al–Mn–Cr–Zr-based alloy system containing three times the equilibrium amounts of Mn and Zr. The alloys were produced via a powder bed fusion-laser beam (PBF-LB) process taking advantage of rapid cooling and solidification characteristics of the process. This supersaturation can then be leveraged to provide high precipitation hardening via direct ageing heat treatments. The hardening is enabled with Zr-rich and Mn-rich precipitates. Literature study confirms that Mn-rich precipitates have a notable solubility of Cr, for example, the Al12Mn precipitate. This study aims to clarify the effect of Cr solubility in the thermodynamics and kinetics simulation and compare the precipitation simulations with samples subject to >1000 h isothermal heat treatment, thus creating an equilibrium-like state. The results show that Cr addition to the precipitates stabilizes the Al12Mn precipitate while slowing the precipitation kinetics thus producing a favourable hardening response. Such observations could be insightful while designing such alloys and optimising heat treatments of the current or even a future alloy system.
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| 10. |
- Olijnik, Aude-Anais, et al.
(författare)
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Genetic and functional insights into CDA-I prevalence and pathogenesis
- 2021
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Ingår i: Journal of Medical Genetics. - : BMJ Publishing Group Ltd. - 0022-2593 .- 1468-6244. ; 58:3, s. 185-195
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Tidskriftsartikel (refereegranskat)abstract
- Background Congenital dyserythropoietic anaemia type I (CDA-I) is a hereditary anaemia caused by biallelic mutations in the widely expressed genes CDAN1 and C15orf41. Little is understood about either protein and it is unclear in which cellular pathways they participate. Methods Genetic analysis of a cohort of patients with CDA-I identifies novel pathogenic variants in both known causative genes. We analyse the mutation distribution and the predicted structural positioning of amino acids affected in Codanin-1, the protein encoded by CDAN1. Using western blotting, immunoprecipitation and immunofluorescence, we determine the effect of particular mutations on both proteins and interrogate protein interaction, stability and subcellular localisation. Results We identify six novel CDAN1 mutations and one novel mutation in C15orf41 and uncover evidence of further genetic heterogeneity in CDA-I. Additionally, population genetics suggests that CDA-I is more common than currently predicted. Mutations are enriched in six clusters in Codanin-1 and tend to affect buried residues. Many missense and in-frame mutations do not destabilise the entire protein. Rather C15orf41 relies on Codanin-1 for stability and both proteins, which are enriched in the nucleolus, interact to form an obligate complex in cells. Conclusion Stability and interaction data suggest that C15orf41 may be the key determinant of CDA-I and offer insight into the mechanism underlying this disease. Both proteins share a common pathway likely to be present in a wide variety of cell types; however, nucleolar enrichment may provide a clue as to the erythroid specific nature of CDA-I. The surprisingly high predicted incidence of CDA-I suggests that better ascertainment would lead to improved patient care.
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