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Negative Additive Manufacturing of Complex Shaped Boron Carbides
Published on: September 18, 2018
Behavior of disordered boron carbide under stress
Giovanni Fanchini1, James W McCauley, Manish Chhowalla
1Materials Science and Engineering, Rutgers University, Piscataway, New Jersey 08854, USA.
Physical Review Letters
|August 16, 2006
Summary
Boron carbide
Area of Science:
- Materials Science
- Computational Materials Science
- Solid-State Physics
Background:
- Boron carbide (B4C) is a high-performance ceramic material.
- Understanding B4C failure mechanisms under extreme conditions is crucial for its applications.
- The Hugoniot elastic limit (HEL) is a key parameter in shock compression studies.
Purpose of the Study:
- To investigate the source of boron carbide failure above the Hugoniot elastic limit (HEL).
- To identify the specific B4C polytype responsible for shock-induced amorphization.
- To elucidate the mechanism of B4C collapse and subsequent phase segregation.
Main Methods:
- Density functional theory (DFT) based Gibbs free-energy calculations.
- Analysis of B4C polytype stability under hydrostatic pressure.
- Determination of energetic barriers for shock amorphization.
Main Results:
- Several B4C polytypes are stable at ambient conditions.
- The B12(CCC) polytype exhibits the lowest energetic barrier for shock amorphization.
- Collapse of B12(CCC) occurs at approximately 6 GPa, leading to B12 and amorphous carbon segregation.
- Amorphous carbon forms 2-3 nm bands along the (113) lattice direction.
Conclusions:
- The B12(CCC) polytype is the primary source of boron carbide failure above the HEL.
- Shock amorphization involves the collapse of the B12(CCC) structure.
- The observed segregation of boron and amorphous carbon aligns with experimental transmission electron microscopy data.
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