The Deformation of Zirconium

 

Certain materials used in modern technology (like those used in extreme environments for the military or nuclear systems) must withstand constantly changing conditions. These conditions include pressure, corrosion and temperature. The creation of next generation materials depends on understanding their lattice like behavior.

Scientists at the Lawrence Livermore National Laboratory are working on a new project. The team have compressed crystals of zirconium. They found that under pressure, the material deformed in surprising ways. The research appeared in two separate letters, Physical Review Letters and Physical Review B. 

Materials under high stress conditions can show a myriad of shear induced amorphization, phase transition, fracture, crystallographic twinning and dislocation slip.

All metal plastically deforms under pressure. This means that they permanently change their shape under pressure. This is due to the motion of defects called dislocations on certain planes in specific crystallographic directions. 

Saransh Soderlind is an LLNL scientist and lead author of the study.  She explained, “The precise knowledge of the crystallographic planes and the direction a material deforms can allow us to develop models describing the mechanical behavior of metals at extreme levels of compression. In our work on zirconium, we employed new experimental techniques, which revealed how elemental metals deform in an unexpected and highly complex way.”

The scientists used femtosecond in-situ X-ray diffraction. They did this to observe the zirconium compressed at high pressures with nanosecond timing. 

The team found a certain atomic disorder. They had never seen this in an elemental metal. They also discovered multiple path ways for crystal transformation, another observation never made before. A machine corroborated the study’s experimental observations. 

Raymond Smith is an LLNL scientist. He reports, “These findings reveal a more intricate picture of deformation in metals under extreme conditions than previously understood. This rich tapestry of atomic movements is likely common place in other materials at high pressure.”

Zirconium alloys are currently used in the nuclear industry. They are used as fuel rod cladding. This is due to zirconium’s high strength and low neutron absorption ability.  Zirconium is also widely used in extreme chemical environments.