Microstructure formation

This article provides answers to the following questions, among others:

  • What is meant by a microstructure?
  • What are grains and grain boundaries?
  • What is a single crystal and a polycrystal?
  • Why is a fine-grained microstructure in metals often desirable?
  • What ist meant by crystallization?
  • Why are monocrystalline materials used for high-temperature applications?
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Conditions of solidification

This article provides answers to the following questions, among others:

  • Which atomic processes take place during solidification?
  • What conditions must be fullfiled for crystallization?
  • What is supercooling?
  • What are nuclei used for in a melt?
  • How is the solidification temperature defined?
  • What conditions must be met for supercooled water?
  • What is freezing rain?
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Types of nuclei

This article provides answers to the following questions, among others:

  • What is homogeneous and heterogeneous nucleation?
  • How can homogeneous nucleation occur in the melt?
  • Which type of nucleation is more likely during solidification?
  • What measures can influence the solidification process so that the structure is as fine-grained as possible?
  • What is meant by seeding of a melt?
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Heat of solidification

This article provides answers to the following questions, among others:

  • Why does the temperature remain constant when pure substances solidify?
  • How can it be explained on a microscopic level that the temperature is kept constant during crystalisation?
  • What is a “thermal arrest”?
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Amorphous metals

This article provides answers to the following questions, among others:

  • What are amorphous metals (metallic glasses)?
  • Why is glass a thermodynamic liquid?
  • What is meant by the term glass transition temperature?
  • What are the technological properties of amorphous metals?
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Homogeneous nucleation

This article provides answers to the following questions, among others:

  • How can the Gibbs energy be used to assess whether a process is voluntary or not?
  • How can the different states of matter be explained?
  • What influence does surface energy have on nucleation?
  • Why are only nuclei above a critical radius stable and can initiate the solidification process?
  • What is the free energy barrier for nucleation?
  • What effect does undercooling have on the rate of nucleation?
  • Why do one suppress crystallization when undercooling is too high?
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Heterogeneous nucleation

This article provides answers to the following questions, among others:

  • How can foreign particles promote nucleation?
  • What is the contact angle?
  • What influences the contact angle?
  • What is the connection between heterogeneous and homogeneous nucleation?
  • What property should a foreign particle have in order to promote nucleation?
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Crystal growth

This article provides answers to the following questions, among others:

  • What is polygonal crystal growth?
  • What distinguishes a microstructure with polygonal crystal growth?
  • What is dendritic crystal growth?
  • What distinguishes a microstructure with dendritic crystal growth?
  • How is the 3-zone casting structure of a casting block formed?
  • What ist microshrinkage?
  • Why does a snowflake have a branched hexagonal shape?
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