Advanced Materials Science: HEAs, Graphene, and Metallic Glasses
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Advanced Materials Science Concepts
High Entropy Alloys (HEAs)
What Materials Are Named ‘High Entropy Alloys’?
Substances constructed with equal or nearly equal quantities of five or more metals. They exhibit a higher degree of fracture resistance, tensile strength, as well as corrosion and oxidation resistance compared to conventional alloys.
What Conditions Must Be Satisfied to Obtain HEA from a Number of Chemical Elements?
Gibb’s phase rule applies: F=C-P+2.
Graphene and Graphene-Like Materials
Differences Between Graphene and Silicene
Silicene is not flat; it is stronger than graphene. Silicene’s hydrogenation reaction is more exothermic than graphene’s.
Three Examples of Graphene-Like Materials
- Layered van der Waals materials
- Graphene-like ZnO
- MXenes
What Are Major Applications of Graphene-Like Materials?
Solar energy cells, electrical batteries, medical applications, LEDs, and the electronics industry.
The Structure of Graphene
Graphene is a 2D, crystalline allotrope of carbon.
Mention the Known Allotropic Forms of Carbon
Diamond, Graphite, Graphene, Nanotube, Fullerene.
Main Properties of Graphene
Good electrical conductivity, ultimate tensile strength, ability to transform light into electricity, and high transparency.
How Many Times Is Graphene Stronger Than Steel Theoretically?
It is hundreds of times stronger than most steels by weight.
Biodegradable Materials
What Properties Are Required for a Material to Be Named Biodegradable?
Upon disposal, all biodegradable polymers should easily break down. They must also be non-toxic and capable of maintaining good mechanical integrity until degradation occurs.
Factors Controlling the Rate of Degradation
- Percent crystallinity
- Molecular weight
- Hydrophobicity
Two Chemical Reactions Taking Place During Biodegradation
Reactions based on oxidation and reactions based on hydrolysis.
What Takes More Time: Composting or Biodegradation?
Biodegradation.
What Are Types of Thermal-Based Biodegradable Films and Their Properties?
Biodegradable polyethylene film, Starch-based or biobased (hydrodegradable) film, Oxodegradable film, and films enhancing polymer hydrophilicity.
Metallic Glasses
Main Difference Between Metallic Glasses and Other Metals
Most metals are crystalline, but metallic glasses are amorphous (non-crystalline).
Main Advantage of Metallic Glasses
Amorphous metals possess good electrical conductivity, low shrinkage during cooling, resistance to plastic deformation, and good resistance to wear and corrosion.
How Many Types of Metallic Glasses Depending on Composition, and What Are They?
- Metal-metal metallic glasses
- Metal-metalloid metallic glasses
Three Applications of Metallic Glasses in Industry
They are used in high-efficiency transformers and electronic article surveillance systems. Furthermore, due to their softening behavior, amorphous metals are used for the thermoplastic forming of metallic glasses.