Induced crystallization method of rapid metal melts 3d-printing

透明有机熔体中形核与结晶过程的物理模拟

Physical simulation of nucleation and crystallization processes in transparent organic melts

该研究利用透明有机熔体液滴法，通过结晶动力学曲线揭示了过热温度、保温时间及过冷度对100÷200 μm液滴形核的影响，证实杂质在异质形核中起决定性作用，为铸造阶段控制铸件组织提供科学依据。

A comparative study of the behaviour of forsterite melts under atmospheric and sub-atmospheric conditions

The study is focussed towards understanding the difference in behaviour of forsterite droplets subjected to sub-atmospheric conditions. Melt droplets, 1.5-2.5 mm in diameter, are made to crystallize under levitated conditions. The spherule is initially superheated by about 250oC above its liquids temperature, for both atmospheric and sub-atmospheric conditions, and then, subsequently cooled at different cooling rates. Crystallization of molten droplets was observed from their hypercooled states in all the cases. It was found that the level of undercooling was more (~150K-200K) for sub-atmosphe…

Rheological Properties of Thermoplastic Polymers with Dissolved Gases for Foaming Applications

Understanding the concept of rheology in polymer melts with dissolved gases like CO2 is crucial in development of high quality polymer foams which are commonly manufactured by foam extrusion processes. The crystallization and rheological properties of the melt are significantly affected by the dissolved gas, which acts as a blowing agent and at the same time as a plasticizer. Moreover, the rheological properties of gas-loaded polymer melts influence on the efficient design of extrusion dies toward production of popular homogenous lightweight foams. This chapter will discuss common methods to m…

Effect of Temperature History During Additive Manufacturing on Crystalline Morphology of Polyether Ether Ketone

Additive manufacturing parameters of high-performance polymers greatly affect the thermal history and consequently quality of the end-part. For fused deposition modeling (FDM), this may include printing speed, filament size, nozzle, and chamber temperatures, as well as build plate temperature. In this study, the effect of thermal convection inside a commercial 3D printer on thermal history and crystalline morphology of polyetheretherketone (PEEK) was investigated using a combined experimental and numerical approach. Using digital scanning calorimetry (DSC) and polarized optical microscopy (POM…

Discovering universal scaling laws in 3D printing of metals with genetic programming and dimensional analysis

We leverage dimensional analysis and genetic programming (a type of machine learning) to discover two strikingly simple but universal scaling laws, which remain accurate for different materials, processing conditions, and machines in metal three-dimensional (3D) printing. The first one is extracted from high-fidelity high-speed synchrotron X-ray imaging, and defines a new dimensionless number, Keyhole number, to predict melt-pool vapor depression depth. The second predicts porosity using the Keyhole number and another dimensionless number, normalized energy density. By reducing the dimensions …

Laser-induced crystallization of copper oxide thin films: A comparison made between Gaussian and chevron-beam profiles provides a clue for the failure of Gaussian-beam profile

The use of laser with a Gaussian-beam profile is frequently adopted in attempts of crystallizing non-single-crystal thin films; however, it merely results in the formation of poly-crystal thin films. In this paper, selective area crystallization of non-single-crystal copper(II) oxide (CuO) is described. The crystallization is induced by laser, laser-induced crystallization, with a beam profile in the shape of chevron. The crystallization is verified by the exhibition of a transition from a non-single-crystal phase consisting of small 100 nm x 100 nm grains of CuO to a single-crystal phase of c…