Phase field modeling of rapid solidification for thin films and additive manufacturing

Tatu Pinomaa

Phase field modeling of rapid solidification for thin films and additive manufacturing

Julkaisun otsikon käännös: Nopean jähmettymisen faasikenttämallinnusta ohutkalvoille ja materiaalia lisäävälle valmistukselle

Tatu Pinomaa

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Useat teolliset metallien valmistusmenetelmät perustuvat nopeaan jähmettymiseen, kuten laserhitsaus, terminen ruiskutus ja materiaalia lisäävä valmistus eli 3D-tulostus. Näin syntyvien materiaalien ominaisuudet eroavat huomattavasti sellaisista materiaaleista, joita valmistetaan hitaan jähmettymisen menetelmillä kuten valamisella. Ero ominaisuuksissa johtuu nopean jähmettymisen aikaansaamista erityisistä mikrorakenteista, jotka riippuvat siitä miten nopea jähmettyminen muuttaa kasvudynamiikkaa. Esimerkkejä nopeasta jähmettymisestä ovat metastabiilien faasien valikoituminen, merkittävä rajapinnankiinnittymiskinetiikka (interface attachment kinetics) ja seosaineen loukkuuntuminen (solute trapping). Näiden ilmiöiden vaikutukset jähmettymiseen pitää ymmärtää perusteellisesti, jotta nopean jähmettymisen menetelmiä voidaan säätää hallitusti, luoda materiaaliin halutut mikrorakenteelliset piirteet, ja lopulta tuottaa toivottavat materiaaliominaisuudet. Näitä riippuvuuksia valmistusmenetelmän, mikrorakenteen ja ominaisuuksien välillä voidaan määrittää laskennallisella mallinnuksella. Viime vuosikymmeninä faasikenttämenetelmästä on tullut tärkein malli jähmettymisen simulointiin mikrorakenteen tasolla. Materiaalitiedeyhteisössä faasikenttämenetelmän suosio perustuu sen yhteydellä statistiseen fysiikkaan ja termodynamiikkaan sekä sillä, että uusia fysikaalisia ilmiöitä voidaan ottaa mukaan näihin malleihin suhteellisen helposti. Tässä väitöskirjassa esitellään laskennallisesti tehokas ja tarkka faasikenttämallinnusmenetelmä joka soveltuu nopeaan jähmettymiseen. Faasikenttämallista tehdään laskennallisesti tehokas mukautuvalla verkon tihennyksellä ja jaettuun muistiin perustuvalla rinnakkaistuksella. Kvantitatiivinen tasapainoa lähellä toimiva faasikenttämalli laajennetaan nopean jähmettymisen alueelle käyttäen menetelmää nimeltä Matched Interface Asymptotics Analysis. Näin seoksen ansautumisen kinetiikkaa voidaan säätää hallitusti vastaamaan niin sanottua Continuous Growth -mallia. Tässä väitöskirjassa kehitettyä nopean jähmettymisen faasikenttämallia sovelletaan materiaalia lisäävään valmistukseen. Ensin menetelmää sovelletaan ruostumattomaan teräkseen valmistusmentelmä-mikrorakenne -riippuvuuksien ymmärtämiseen. Lopuksi tutkitaan inokuloinnin vaikutusta monikiderakenteisiin. Tässä väitöskirjassa kehitetyn nopean jähmettymisen faasikenttämalli edistää uusien teknillisten materiaalien systemaattista suunnittelua.

Julkaisun otsikon käännös	Nopean jähmettymisen faasikenttämallinnusta ohutkalvoille ja materiaalia lisäävälle valmistukselle
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Ala-Nissilä, Tapio, Vastuuprofessori Laukkanen, Anssi, Ohjaaja, Ulkoinen henkilö Provatas, Nikolas, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-64-0008-2
Sähköinen ISBN	978-952-64-0009-9
Tila	Julkaistu - 2020
OKM-julkaisutyyppi	G5 Tohtorinväitöskirja (artikkeli)

Tutkimusalat

nopea jähmettyminen
faasikenttämallinnus
materiaalia lisäävä valmistus

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-64-0009-9

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@phdthesis{74f90d811afa40a095ec2210fe4cc340,

title = "Phase field modeling of rapid solidification for thin films and additive manufacturing",

abstract = "Several advanced industrial manufacturing processes operate in rapid solidification conditions, including laser welding, thermal spray coating deposition, and additive manufacturing. These processes lead to materials with drastically altered properties, when compared to low solidification rate manufacturing methods such as casting. This is due to the unique microstructural features emerging in rapid solidification. Rapid solidification conditions alter growth dynamics, for example through kinetically selected metastable phases, notable interface attachment kinetics, and solute trapping. Therefore there is a strong motivation to adjust these manufacturing processes to target specific microstructures, in order to reach desirable material properties. These process-structure-property links can be established by computational modeling. In the past decades, the phase field method has become the state-of-the-art model to simulate solidification on microstructural scales. Its success in the materials science community can be attributed to its connection to statistical physics and thermodynamics, simplicity, and relative ease with which new physical phenomena can be implemented. In this thesis, a computationally efficient and quantitative phase field modeling framework is presented for the rapid solidification regime. The phase field model is made computationally efficient through adaptive mesh refinement and shared memory parallelization. A quantitative near-equilibrium alloy phase field model is extended to operate in the rapid solidification regime through matched interface asymptotics analysis, allowing for controllable solute trapping kinetics that follow the continuous growth model in the thin interface limit. The rapid solidification simulations are compared to thin film solidification experiments with time-resolved in-situ imaging. This phase field model is applied to the study of additive manufacturing, first for stainless steel to understand the process-microstructure relationships, and then as a method to investigate the effects of inoculation to alter the polycrystalline structures. The presented rapid solidification phase field modeling framework will assist systematic process-structure-properties based design of novel engineering materials.",

keywords = "rapid solidification, phase field modeling, additive manufacturing, nopea j{\"a}hmettyminen, faasikentt{\"a}mallinnus, materiaalia lis{\"a}{\"a}v{\"a} valmistus, rapid solidification, phase field modeling, additive manufacturing",

author = "Tatu Pinomaa",

year = "2020",

language = "English",

isbn = "978-952-64-0008-2",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "126",

address = "Finland",

school = "Aalto University",

}

TY - THES

T1 - Phase field modeling of rapid solidification for thin films and additive manufacturing

AU - Pinomaa, Tatu

PY - 2020

Y1 - 2020

N2 - Several advanced industrial manufacturing processes operate in rapid solidification conditions, including laser welding, thermal spray coating deposition, and additive manufacturing. These processes lead to materials with drastically altered properties, when compared to low solidification rate manufacturing methods such as casting. This is due to the unique microstructural features emerging in rapid solidification. Rapid solidification conditions alter growth dynamics, for example through kinetically selected metastable phases, notable interface attachment kinetics, and solute trapping. Therefore there is a strong motivation to adjust these manufacturing processes to target specific microstructures, in order to reach desirable material properties. These process-structure-property links can be established by computational modeling. In the past decades, the phase field method has become the state-of-the-art model to simulate solidification on microstructural scales. Its success in the materials science community can be attributed to its connection to statistical physics and thermodynamics, simplicity, and relative ease with which new physical phenomena can be implemented. In this thesis, a computationally efficient and quantitative phase field modeling framework is presented for the rapid solidification regime. The phase field model is made computationally efficient through adaptive mesh refinement and shared memory parallelization. A quantitative near-equilibrium alloy phase field model is extended to operate in the rapid solidification regime through matched interface asymptotics analysis, allowing for controllable solute trapping kinetics that follow the continuous growth model in the thin interface limit. The rapid solidification simulations are compared to thin film solidification experiments with time-resolved in-situ imaging. This phase field model is applied to the study of additive manufacturing, first for stainless steel to understand the process-microstructure relationships, and then as a method to investigate the effects of inoculation to alter the polycrystalline structures. The presented rapid solidification phase field modeling framework will assist systematic process-structure-properties based design of novel engineering materials.

AB - Several advanced industrial manufacturing processes operate in rapid solidification conditions, including laser welding, thermal spray coating deposition, and additive manufacturing. These processes lead to materials with drastically altered properties, when compared to low solidification rate manufacturing methods such as casting. This is due to the unique microstructural features emerging in rapid solidification. Rapid solidification conditions alter growth dynamics, for example through kinetically selected metastable phases, notable interface attachment kinetics, and solute trapping. Therefore there is a strong motivation to adjust these manufacturing processes to target specific microstructures, in order to reach desirable material properties. These process-structure-property links can be established by computational modeling. In the past decades, the phase field method has become the state-of-the-art model to simulate solidification on microstructural scales. Its success in the materials science community can be attributed to its connection to statistical physics and thermodynamics, simplicity, and relative ease with which new physical phenomena can be implemented. In this thesis, a computationally efficient and quantitative phase field modeling framework is presented for the rapid solidification regime. The phase field model is made computationally efficient through adaptive mesh refinement and shared memory parallelization. A quantitative near-equilibrium alloy phase field model is extended to operate in the rapid solidification regime through matched interface asymptotics analysis, allowing for controllable solute trapping kinetics that follow the continuous growth model in the thin interface limit. The rapid solidification simulations are compared to thin film solidification experiments with time-resolved in-situ imaging. This phase field model is applied to the study of additive manufacturing, first for stainless steel to understand the process-microstructure relationships, and then as a method to investigate the effects of inoculation to alter the polycrystalline structures. The presented rapid solidification phase field modeling framework will assist systematic process-structure-properties based design of novel engineering materials.

KW - rapid solidification

KW - phase field modeling

KW - additive manufacturing

KW - nopea jähmettyminen

KW - faasikenttämallinnus

KW - materiaalia lisäävä valmistus

KW - rapid solidification

KW - phase field modeling

KW - additive manufacturing

M3 - Doctoral Thesis

SN - 978-952-64-0008-2

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Phase field modeling of rapid solidification for thin films and additive manufacturing

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