Rapid material development and processing of complex near-net-shaped parts by PIM

A promising fabrication method in view of large-scale production of complex parts is Powder Injection Molding (PIM) which has been intensively investigated at Karlsruhe Institute of Technology (KIT). With its near-net-shape precision the method offers particularly the advantage of cost-saving. PIM as special process allows the mass production of components, the creation of composite and prototype materials. Furthermore it is an ideal tool for scientific investigations for R&D in general, and for developing industrial products for a wide range of applications. This contribution describes the characterization and analyses of prototype materials produced via PIM. The investigation of pure tungsten and oxide or carbide doped tungsten materials comprises the microstructure examination, element allocation, texture analyses, and mechanical testing. In addition, fabricated near-net-shape Langmuir probes for diagnostics for the French tokamak WEST will be presented

Exploring the mechanical character of molybdenum grain boundaries via nanoindentation and three-point-bending

The interactions of interfaces with dislocations have been extensively studied in the past. Still, there is a lack of high throughput methods, which can potentially be used for systematic studies to cover a wide range of grain boundary types. Nanoindentation offers the opportunity to combine a high spatial resolution with high effectiveness, thus enabling to obtain comprehensive mechanical data in the vicinity of grain boundaries. The present study on coarse-grained molybdenum will show results of mechanical property mapping near grain boundaries. Here, for the first time also the indenter tip rotation angle with respect to the loading axis as well as the grain orientation are considered. Results will show that neglecting these parameters can bias interpretations of the interface/dislocation interactions, as the localized deformation paths around the indentation are thereby significantly changed. Systematic experiments on commercially pure, recrystallized molybdenum have been performed to investigate the dependence of the hardness increase near grain boundaries with respect to the boundary misorientation angle. As a complementary method, three-point-bending is applied on mm-sized specimens until individual grain boundaries delaminate, which in turn will be identified and cross-checked with findings of the nanoindentation tests. Doping molybdenum with elements like carbon and/or boron is known to suppress intercrystalline failure. For this reason, the presented grain boundary characterization methods will be applied to extract mechanical changes caused by these doping elements

2015 EXCELLENCE IN METALLOGRAPHY AWARD EVOLUTION OF STRAIN-INDUCED PRECIPITATES IN A MOLYBDENUM-BASE Mo-Hf-C ALLOY

The powder metallurgy processed molybdenumbase alloy Mo-Hf-C (MHC) Dallinger,**** Helmut Clemens***** and Sophie Primig****** INTRODUCTION The particle-hardened alloy Mo-Hf-C (MHC) is processed via a powder metallurgy (PM) route. It is known for its high strength at elevated temperatures and its high recrystallization temperatures. Its nominal composition of 0.65 at.% Hf and 0.65 at.% C has been derived from various investigations of arc melted and solution-annealed Mo-Hf-C alloys in the 1960s and 70s. In particular, an alloy with a similar composition to MHC exhibited superior properties after swaging. In contrast to PM processed MHC, all the hafnium and carbon content of the solution-annealed material is in solid solution. The carbon and the hafnium contents of MHC are adjusted in order to produce ~1 vol.% hafnium carbide. 1-3 After sintering, the microstructure of MHC consists of a molybdenum matrix, hafnium-oxide particles (5-10 µm diameter), molybdenum carbides decorating the grain boundaries, and large hafnium carbides (1 µm diameter, ~80 nm thick). The residual hafnium content in solid solution is ~0.10-0.15 at.% and the typical microporosity is ~4%. For a full exploitation of the precipitation potential of the MHC alloy, it i

Estrogen receptor promoter methylation predicts survival in low-grade ovarian carcinoma patients

Ovarian carcinoma is the third most common gynecological cancer and only short recurrence-free survival and overall survival times are archived. The role of the estrogen receptor expression is well studied in breast cancer and breast cancer cell lines. Patients with positive estrogen receptor expression have a lower risk for recurrence and a better overall survival. Previous studies have shown that ESR1 methylation influences ovarian cancer development and might thus play a role regarding prognosis of ovarian carcinoma. A total of 75 patients were identified that were treated for ovarian carcinoma by debulking surgery and adjuvant standard chemotherapy. Isolation and bisulfite treatment of genomic DNA from serial sections of surgically resected ovarian carcinoma tissue was performed using commercially available kits. For the detection of methylated ESR1 promoter sequences, real-time methylation-specific PCR was used. Promoter methylation did not show a correlation between clinical-pathological data for all patients. However, within the subgroup of low-grade ovarian carcinoma patients and patients with an ovarian tumor of low malignant potential methylation of the ESR1 promoter inversely correlated with survival (p = 0.031). Although small numbers of ovarian carcinoma patients were analyzed, methylation status might be useful as a prognostic marker within the subgroup of low-grade ovarian carcinoma patients. Further studies should investigate a larger cohort and also address the use of demethylation agents with respect to improve patient's prognosis in this subgroup of ovarian carcinoma patients