Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

Abstract

It has been a tremendous challenge to manufacture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the requirements of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room temperature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nano-scale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load-displacement curves during nanoindentation.

Keywords

Potassium dihydrogen phosphate (KDP) crystals / Creep-deformation / Stress / Dislocation

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Funding

Natural Science Foundation of Heilongjiang Province (CN)(No. E2018033)

ARC(No. DP170100567)

NSFC(No. 51375122)