Heterostructured crystallization mechanism and its effect on enlarging the processing window of Fe-based nanocrystalline alloys

The harsh melt-spinning and annealing processes of high saturation magnetization nanocrystalline softmagnetic alloys are the biggest obstacles for their industrialization. Here, we proposed a novel strategy to enlarge the processing window by annealing the partially crystallized precursor ribbons via a heterostructured crystallization process. The heterostructured evolution of Fe_(84.75)Si_(2)B_(9)P_(3)_(C0.5)Cu_(0.75)(at.%)alloy ribbons with different spinning rate were studied in detail, to demonstrate the gradient nucleation and grain refinement mechanisms. The nanocrystalline alloys made with industrially acceptable spinning rate of 25-30 m/s and normal annealing process exhibit excellent magnetic properties and fine nanostructure. The small quenched-in crystals/clusters in the free surface of the low spinning rate ribbons will not grow to coarse grains, because of the competitive grain growth and shielding effect of metalloid elements rich interlayer with a high stability. Avoiding the precipitation of quenched-in coarse grains in precursor ribbons is thus a new criterion for the composition and process design, which is more convenient than the former one with respect to the homogenous crystallization mechanism, and enable us to produce high performance nanocrystalline soft-magnetic alloys. This strategy is also suitable for improving the compositional adjustability, impurity tolerance, and enlarging the window of melt temperature,which is an important reference for the future development of composition and process.

Principle and Process Window of Cerium Dioxide Thin Film Fabrication with Dual Plasma Deposition

Cerium dioxide, CeO2, is a potentially superior material in a myriad of areas, and many methods have been proposed to deposit single crystal CeO2 thin films. A novel fabrication technique utilizing dual plasma generated by metal vacuum arc (MEVVA) and radio frequency (RF) is discussed in this paper. We have recently conducted a systematic investigation to determine the optimal process window to deposit CeO2 thin films’on Si(100) substrates. The X-ray diffraction results show the existence of CeO2(100) in the as-deposited sample.

Effect of alloying elements on austempered ductile iron(ADI) properties and its process:Review

Austempered ductile iron(ADI) parts have a unique combination of high strength and toughness with excellent design flexibility and low cost. These excellent properties are directly related to its microstructure called "ausferrite" that is the result of austempering heat treatment applied to ductile irons. Alloying elements increase ADI austemperability and change speeds of austempering reactions. Thus, they can affect ADI resultant microstructure and mechanical properties. In this paper, the effects of alloying elements on ADI mechanical properties, microstructural changes, two-stage austempering reactions, processing windows, austemperability, and other aspects are reviewed.

Pattern-Centric Computational System for Logic and Memory Manufacturing and Process Technology Development

Chip designers employ computer-aided design,circuit simulation,and design rule check systems.Lithography engineers employ model-based OPC(Optical Proximity Correction)and model-based print-simulation systems.Reticle inspection teams employ Aerial Image Measurement Systems®and Virtual Stepper®Systems.These teams are accustomed to evaluating and deploying state-of-the-art computational systems.When real-silicon fabrication begins,however,the teams responsible for line monitoring,wafer inspection,and yield attainment operate without the benefit of similarly advanced computational systems.In this paper we describe such a system and explore its applications and benefits.The system has received three U.S.patents[1-3]and brings together the significant potential of CAD(Computer Aided Design)layout(GDS,OASIS),Die-to-Database,and Machine Learning to build a dynamic,self-improving computational system.Featuring care area generation,advanced machine learning-based SEM(Scanning Electron Microscope)sampling that optimizes both DOI(Defect of Interest)capture rate and discovery of new defect types,comprehensive extraction of all Information of Interest(IOI)from all SEM images,detection of defect types not possible before,massive pattern fidelity analysis,full chip pattern decomposition and risk scoring via machine learning,innovative PWQ(Process Window Qualification)analysis and process window determination,risk assessment of new tape-outs,large scale in-wafer OPC verification and more,the system delivers a comprehensive pattern centric platform for process technology development and manufacturing.

Processing map of as-cast 7075 aluminum alloy for hot working

The true stress-strain curves of as-cast 7075 aluminum alloy have been obtained by isothermal compression tests at temperatures of 300 500 ~C and strain rates of 0.01 10 s i. The plastic flow instability map is established based on Gegel B and Murthy instability criteria because the deformed compression samples suggest that the combination of the above two instability criteria has more comprehensive crack prediction ability. And the processing map based on Dynamic Mate- rial Model （DMM） of as-cast 7075 aluminum alloy has been developed through a superposition of the established instability map and power dissipation map. In terms of microstructure of the deformed samples and whether plastic flow is stable or not, the processing map can be divided into five areas： stable area with as-cast grain, stable area with homogeneous grain resulting from dynamic recovery, instability area with as-cast grain, instability area with the second phase and instability area with mixed grains. In consideration of microstructure characteristics in the above five areas of the processing map, the stable area with homogeneous grain resulting from dynamic recovery, namely the temperatures at 425465 ℃ and the strain rates at 0.01^-1 s^-1, is suggested to be suitable processing window for the as-cast 7075 aluminum alloy.

Exit morphology and mechanical property of FDM printed PLA: influence of hot melt extrusion process

In order to study the hot melt extrusion process in fused deposition modeling(FDM),this study mainly explores the effects of printing temperature,heated block length,feeding speed on the exit morphology and mechanical properties of FDM printed Polylactic acid(PLA)samples.High-speed camera is used to capture the exit morphology of molten PLA just extruded to the nozzle.According to exit morphology,the outlet states of extruded molten material can be divided into four categories,namely,bubbled state,coherent state,expanding state,and unstable state.Tensile test results show that printing temperature,heated block length and printing speed have significant influence on tensile properties and fracture mode of FDM printed samples.When the heated block length is 15 mm and 30 mm,there is a ductile-brittle transition in fracture mode with the increase of printing speed.The printing process window under different heated block lengths and printing temperatures has been figured out and the distribution of printing process window under different printing speeds has been discussed.There is a maximum printing process window under the heated block length of 30 mm.This finding provides a frame work for performance prediction of FDM printed parts and theoretical guidance for expanding the scope of printing process window.

Electrically Actuated Shape Recovery of NiTi Components Processed by Laser Powder Bed Fusion after Regulating the Dimensional Accuracy and Phase Transformation Behavior

To develop self-recovery intelligent components based on resistance heating and obtain satisfactory performance in practical applications,this study optimized the forming quality,dimensional accuracy,and phase transformation temperatures of Nickel-titanium(NiTi)alloys by controlling the process parameters.The tensile properties and shape-memory effects of the NiTi alloys prepared using the optimized process were clarified.The relationship between the change in temperature and the shape recovery process of the deformed structure under electrical excitation was investigated.The results show that the suitable processing window for ensuring the forming quality without noticeable distortion and macro cracks depends on the laser parameters.In both the X and Y directions,the measured dimensions increased with an increase in laser power and first decreased and then stabilized with an increase in scanning speed.The XRD results showed that all the as-built samples consisted of B2 austenite and B19’martensite phases and Ni3Ti.Mechanical tests suggested that excellent tensile properties with a tensile strength of 753.28 MPa and elongation of 6.81%could be obtained under the optimal parameters of 250 W and 1200 mm/s.An excellent shape-recovery rate of 88.23%was achieved under the optimal parameters.Subsequently,chiral lattice structures were successfully fabricated by laser powder bed fusion(LPBF)under the optimal parameters,and a shape-recovery rate of 96.7%was achieved under electrical actuation for a structure with a pre-compressed strain of 20%.This study also found that the temperatures at the grasp regions were always higher than those at other positions because of the generation of contact resistance at the grasp regions.This facilitates the rapid recovery of the structure at the grasp regions,which has important implications for the design iteration of NiTi smart components.

Fast Level-Set-Based Inverse Lithography Algorithm for Process Robustness Improvement and Its Application

Inverse lithography technology （ILT） is one of the promising resolution enhancement techniques （RETs）, as the advanced integrated circuits （IC） technology nodes still use the 193 nm light source. Among all the algorithms for ILT, the level-set-based ILT （LSB-ILT） is a feasible choice with good production result in practice. However, existing ILT algorithms optimize masks at nominal process condition without giving sufficient attention to the process variations, and thus the optimized masks show poor performance with focus and dose variations. In this paper, we put forward a new LSB-ILT algorithm for process robustness improvement with fast convergence. In order to account for the process variations in the optimization, we adopt a new form of the cost function by adding the objective function of process variation band （PV band） to the nominal cost. We also adopt the hybrid conjugate gradient （CG） method to reduce the runtime of the algorithm. We perform experiments on ICCAD 2013 benchmarks and the results show that our algorithm outperforms the top two winners of the ICCAD 2013 contest by 6.5%. We also adopt the attenuated phase shift mask （att-PSM） in the experiment with test cases from industry. The results show that our new algorithm has a fast convergence speed and reduces the process manufacturability index （PMI） by 38.77% compared with the LSB-ILT algorithm without the consideration of PV band.