Selective laser melting (SLM) of Ti6Al4V is a very promising method to produce complex geometries for challenging impact applications. Hot isostatic pressing (HIP) is typically used to improve fatigue behavior, ductility and material reliability of parts produced by SLM. However, this treatment leads to an undesired deterioration of strength. The present study addresses that issue by investigating the effect of two different HIP conditions on the mechanical properties under compression and tensile loading for a strain rate range spanning up to 6 order of magnitudes and two different temperatures. We found a significant tensile-compression anisotropy in both flow stress and strain rate sensitivity depending on the HIP temperatures. These findings was correlated with microstructures and damage mechanisms.

Abstract Additive Manufacturing is doing its first steps in the production of spare parts. Usually the spares belong to legacy systems, and the tooling to produce them is no longer available. Re-designing spares that are designed for a previous industry mindset can be sometimes challenging. In this study a rather classic design approach is compared to a functional driven approach. Four case studies from different clients are reported, remarking the benefits and drawbacks of using design for additive manufacturing practices in Laser Powder Bed Fusion.

Abstract The topic of support structure design in the Design for Additive Manufacturing (DfAM) field is not addressed with the same relevance as the topic of part design. Therefore, this contribution investigates parameters for both the manufacturing and support structure design for the Laser Powder Bed Fusion (L-PBF) process. Matrices for cause-effect-relations of manufacturing and design parameters on build properties as well as correlations of them are presented. Based on these, recommendations for actions for experimental procedures are derived following the Design of Experiments method.

This paper presents results about the influence of the selective laser melting (SLM) process parameters on a FeCr4Mo1V1W8C1 (wt%) alloy regarding microstructure and mechanical behavior. Tailored parameter variation studies were performed to obtain crack-free and highly dense SLM parts. The microstructure was studied using scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy, and scanning transmission electron microscopy. Additionally, the mechanical properties were investigated by compression and tensile tests. The obtained microstructure is composed of complex nanoscale carbides, retained austenite, and martensite. Caused by the fast directional cooling during SLM, a completely dendritic solidification aligned in building direction occurs. Non-equilibrium segregation leads to an orderly phase arrangement of complex carbides at the boundary of the dendrites surrounded by retained austenite and martensite in the center of the dendrites. A strong work hardening behavior was observed, based on an austenite-to-martensite phase transformation (TRIP effect). This effect accounts for the outstanding mechanical properties such as compression strength of 6000 MPa, a 0.2% tensile yield strength of 560 MPa, and an ultimate tensile strength of over 1000 MPa. These findings reveal that SLM is advantageous for the processing of ultra-high-strength FeCrMoVWC tool steel.

This study examined into the surface roughness and microhardness of titanium (Ti6Al4V) alloy caused by the abrasive waterjet milling (AWJM) process. Waterjet pressure (WJP), stand-off distance (SOD), and abrasive flow rate (AFR) were studied on surface roughness and microhardness in three distinct regions: the initial damage region (IDR), the smooth cutting region (SCR) and the rough cutting region (RCR). X-Ray Diffraction was used to examine the lattice strain, crystallite size, and phase composition of abrasive waterjet machined samples. WJP is discovered to be a useful factor in reducing surface roughness, increasing striations, and decreasing waviness on the AWJM's surface. The higher hardness is caused by the material's permanent plastic deformation during the AWJM process. The FWHM of AWJ machined samples is reduced, and the presence of TiOxCx increases the crystallite size during the AWJM process. In relation to surface deformation, the AWJM causes severe plastic deformation (SPD), resulting in continuous internal oxide formation.

Due to the continued interest in reducing weight in both automobile and aerospace structures, interest has grown in magnesium based alloys as a possible materials solution. Despite this interest, these alloys have not been widely utilized due to their relatively poor mechanical properties in comparison to other material systems. However, recent research has clearly indicated that improved mechanical properties can be achieved in these alloys through the use of severe plastic deformation processing methods. In this report, we examine the influence of equal channel angular pressing on the mechanical response of Elektron 675, a Mg–Gd–Y alloy. Results indicate that an appreciable increase in total elongation and absorbed energy can be obtained depending on the selected processing route. However, these improvements in elongation are somewhat offset by a slight reduction in tensile strength. The observed mechanical response is explained through microstructural analysis as well as texture measurements.

In this work a systematic investigation of the influence of the cooling rate on the microstructure and properties of a newly developed Fe92.7Cr4.2V2.1C1 (FeCrVC) tool steel is presented. By applying a tailored casting process and sufficiently high cooling rates excellent mechanical properties are obtained for the presented alloy already in the as-cast state. Since no subsequent heat treatment is required, the cooling parameters applied during the casting process play a key role with respect to the evolving microstructure and resulting properties. In the present publication the effect of the cooling rate on the microstructure and properties of as-solidified FeCrVC was investigated. By using differential scanning calorimetry (DSC), several samples were heated up and cooled with continuous rates of 3-50 K/min. The received DSC data was used to investigate the alloy's solidification and phase transformation behavior. Subsequently, these samples were studied regarding their properties and microstructure by different analysis methods (EDX/WDX, EBSD, XRD). With increasing cooling rates the liquidus and solidus temperature are lowered, whereas the solidification interval is enlarged. A higher cooling rate is accompanied by a lower solidification time which results in a refinement of the dendritic microstructure. Furthermore, with rising cooling rates the microhardness increased. This provides the opportunity to make predictions from the applied cooling parameters upon the hardness and vice versa and enables one to draw first conclusions on the mechanical properties of the FeCrVC alloy. (C) 2015 Elsevier B.V. All rights reserved.

Starting from the bulk glass-forming composition Mg59.5Cu22.9Ag6.6Gd11, the development of a bulk glassy matrix composite alloy with high strength and ductility was attempted by adding a large amount of Sc to induce the formation of the MgSc intermetallic compound. However, copper-mould casting of the modified composition, Mg54.7Cu11.5Ag3.3Gd5.5Sc25, as rods with 3 and 5 mm diameter, yields besides the expected MgSc, a second (CuSc) and a third (Mg3Gd-type) intermetallic. These compounds are surrounded by a Mg-rich matrix, possibly composed of glassy regions and a Mg-based terminal solid solution. Although the obtained microstructure deviates largely from the expected one, the new alloy exhibits very high strength, i.e. 790 MPa, and visible plastic deformation, i.e. 0.9%. Shear dimples were found in MgSc. (C) 2013 Elsevier Ltd. All rights reserved.

We present a detailed study of the field dependent specific heat of the bimetallic ferromagnetically coupled chain compound MnNi(NO2)4(en)2, en = ethylenediamine. For this material, which in zero field orders antiferromagnetically below TN = 2.45 K, small fields suppress magnetic order. Instead, in such fields a double-peak like structure in the temperature dependence of the specific heat is observed. We attribute this behavior to the existence of an acoustic and an optical mode in the spin wave dispersion as result of the existence of two different spins per unit cell. We compare our experimental data to calculations for a S1 = 1, S2 = 5/2 mixed spin chain. Our calculations on a finite chain of five S1 plus five S2 spins in external fields incorporate the finite ionic zero-field splitting and fully reproduce the double-peak like structure as well as its field dependence.

The tetragonal compound UPt2Si2 has been characterized as a moderately mass-enhanced system with an anti-ferromagnetic (AFM) ground state below T-N = 32 K. Here, we present an extensive study of the behavior in high magnetic fields. We have performed pulsed field magnetization and static field resistivity measurements on single crystalline samples UPt2Si2. Along the crystallographic a axis, at low temperatures, we find a metamagnetic-like transition in fields of the order 40 T, possibly indicating a first-order transition. Along the crystallographic c axis, in magnetic fields of B >= 24 T, we find distinct anomalies in both properties. From our analysis of the data we can distinguish new high-field phases above the AFM ground state. We discuss the emergence of these new phases in the context of Fermi surface effects and the possible occurrence of a Lifshitz or electronic topological transition, this in contrast to previous modelings of UPt2Si2 based on crystal electric field effects.

We present a study of the main bulk properties (susceptibility, magnetization, resistivity and specific heat) of CePt_3B_(1-x)Si-x, an alloying system that crystallizes in a noncentrosymmetric lattice, and derive the magnetic phase diagram. The materials at the end point of the alloying series have previously been studied, with CePt_3B established as a material with two different magnetic phases at low temperatures (antiferromagnetic below T_N = 7.8 K, weakly ferromagnetic below T_C 5 K), while CePt3Si is a heavy fermion superconductor (T_c = 0.75 K) coexisting with antiferromagnetism (T_N = 2.2 K). From our experiments we conclude that the magnetic phase diagram is divided into two regions. In the region of low Si content (up to x 0.7) the material properties resemble those of CePt3B. Upon increasing the Si concentration further the magnetic ground state continuously transforms into that of CePt3Si. In essence, we argue that CePt_3B can be understood as a low pressure variant of CePt3Si.

CePt3B exhibits two magnetic phases, an antiferromagnetic and a weak ferromagnetic one. To determine these magnetic structures of CePt3B, neutron diffraction and μSR experiments have been carried out. Neutron diffraction experiments provided no evidence of either antiferromagnetic or ferromagnetic order. In contrast, in zero field muon-spin relaxation (μSR) experiments, magnetic transition temperatures TN = 7.8 K and TC ~ 6 K are observed from the onset of spontaneous muon precession.

We present bulk magnetic and transport measurements and x-ray resonant scattering measurements on U(Pd1-xPtx)(3) for x = 0.005 and 0.01, which demonstrate the high sensitivity of the quadrupolar order in the canonical antiferroquadrupolar ordered system UPd3 to doping with platinum. Bulk measurements for x = 0.005 reveal behavior similar to that seen in UPd3, albeit at a lower temperature, and x-ray resonant scattering provides evidence of quadrupolar order described by the Q(xy) order parameter. In contrast, bulk measurements reveal only an indistinct transition in x = 0.01, consistent with the observation of short-range quadrupolar order in our x-ray resonant scattering results.

We present bulk magnetic and transport measurements and x-ray resonant scattering measurements on U(Pd1-xPtx)₃ for x=0.005 and 0.01, which demonstrate the high sensitivity of the quadrupolar order in the canonical antiferroquadrupolar ordered system UPd₃ to doping with platinum. Bulk measurements for x=0.005 reveal behavior similar to that seen in UPd₃, albeit at a lower temperature, and x-ray resonant scattering provides evidence of quadrupolar order described by the Qxy order parameter. In contrast, bulk measurements reveal only an indistinct transition in x=0.01, consistent with the observation of short-range quadrupolar order in our x-ray resonant scattering results.

We present a detailed comparison of the physical properties of as-cast and annealed single crystalline UPt2Si2, a compound whose properties we have shown to be governed by strain disorder on the Pt/Si ligand sites. Contrary to common knowledge, and to our surprise, from our data we do not observe a significant improvement of the physical properties of UPt2Si2 upon annealing at 900°C for one week. We attribute this to the specific way the strain disorder is produced in UPt2Si2 by presenting evidence that it results from a first order phase transition at ambient temperatures. We discuss the implications of such phase transitions occurring at comparatively low temperatures for the ground state properties of heavy fermion systems and related correlated electron materials.

High field magnetization measurements have been performed on single crystalline tetragonal UPt2Si2 for the crystallographic a and c directions. These results are compared to previous experiments and calculations based on a crystal electric field scheme. Our analysis indicates that the magnetization, while reproducing previous measurements, strongly deviates from the predictions of the crystal electric field scheme model for both crystallographic directions. This finding indicates that the magnetic behavior of UPt2Si2 is more adequately described within an itinerant approach.

We report the magnetic structure of the recently discovered mass enhanced antiferromagnet UPd2Sb, with an antiferromagnetic transition temperature of TN=55K. Our results have been obtained by analyzing the difference spectra of neutron scattering experiments carried out at low temperatures of 60 and 1.6K. Furthermore, the temperature dependence of the antiferromagnetically ordered moment has been determined. The antiferromagnetic phase consists of ferromagnetic planes spanned by two cubic axes of the Heusler lattice, which are antiferromagnetically coupled along the third axis. From a comparison of magnetic and structural peak intensity the ordered moment was determined to μord=1.3μB at zero temperature. The antiferromagnetic phase is characterized by a short magnetic correlation length of the order of 100Å, this as result of structural disorder in this compound.

We have made an extensive study of PrB6 using x-ray resonant scattering to investigate both the lattice and magnetic properties. We have identified a structural distortion associated with the incommensurate to commensurate magnetic phase transition at T=4.5 K. Magnetic satellite reflections have been observed in the incommensurate and commensurate phases. The azimuthal dependence of the scattered intensity from the commensurate magnetic satellite reflection at (1/2, 5/4, 5/4) is consistent with the model for the magnetic structure deduced from earlier neutron-diffraction results. Evidence for possible quadrupolar ordering is discussed.

We report the magnetic structure of the recently discovered mass enhanced antiferromagnet UPd2SbUPd2Sb, with an antiferromagnetic transition temperature of TN=55K. Our results have been obtained by analyzing the difference spectra of neutron scattering experiments carried out at low temperatures of 60 and 1.6 K. Furthermore, the temperature dependence of the antiferromagnetically ordered moment has been determined. The antiferromagnetic phase consists of ferromagnetic planes spanned by two cubic axes of the Heusler lattice, which are antiferromagnetically coupled along the third axis. From a comparison of magnetic and structural peak intensity the ordered moment was determined to μord=1.3μBμord=1.3μB at zero temperature. The antiferromagnetic phase is characterized by a short magnetic correlation length of the order of 100 A, this as result of structural disorder in this compound.