Processing Characteristics Analysis And Finite Element Simulation Of Gallium Oxide Crystal Based On Nano Indentation

Single crystal gallium oxide（β-Ga₂O₃）has a series of remarkable characteristics,such as band gap width of 4.9 eV,and is a new semiconductor material with very broad application prospects.At the same time,β-Ga₂O₃is a hard brittle crystal with obvious anisotropy and easy cleavage.It is a typical difficult to machine material.Ultra precision machining is particularly difficult,which seriously restricts the application of gallium oxide crystal in the optoelectronic field.Therefore,a comprehensive analysis of its mechanical properties and Research on its machining characteristics become an urgent need to solve the key technical problems.Based on the nanoindentation scratch test,this paper studies the processing characteristics ofβ-Ga₂O₃crystals,and preliminarily determines the processing range of the plastic domain ofβ-Ga₂O₃crystals,as well as the easy-to-machine crystal planes and easy-to-machine crystal orientations during the processing.Combined with the Hopkinson pressure bar test,the constitutive model ofβ-Ga₂O₃crystal was established.After verifying the rationality of the model,the finite element simulation of the cleavableβ-Ga₂O₃crystal processing process was carried out,and compared with the results of the nano-scratch test and stress field analysis,the crack nucleation position and propagation of the gallium oxide material during the processing were obtained.To provide theoretical guidance for practical ultra-precision machining,the main research contents of this paper are as follows:（1）The（010）and（100）crystal planes of theβ-Ga₂O₃crystal are divided into regions at intervals of 15°,and quasi-static nanoindentation tests are performed on different regions.The data output on the indenter was recorded,and the variation law of hardness,elastic modulus and fracture toughness of different crystal planes and different grain directions was obtained.（2）The（010）and（100）crystal planes ofβ-Ga₂O₃crystals are divided into regions at intervals of 15°,and nano-scratch tests with variable loads are performed on different regions.The data output by the indenter was recorded,combined with the quasi-static indentation test,the critical depth of brittle-plastic transition and the critical load were determined,and the values of dimensionless parameters related to the processing technology and the shape of the abrasive particles were further calculated.（3）Based on fracture mechanics,by fitting the data of quasi-static indentation test and Hopkinson compression bar test ofβ-Ga₂O₃crystal,the values of rate-strain parameters,pressure parameters and damage model parameters of gallium oxide crystals are obtained.On this basis,a set of HJC constitutive models forβ-Ga₂O₃crystals are established.The established constitutive model is brought into the ABAQUS simulation software to simulate the quasi-static indentation test ofβ-Ga₂O₃crystal,which further verifies the rationality of the constitutive model.（4）Based on the mechanics of materials,the elastic stress field model of the single abrasive grain on the（010）crystal plane ofβ-Ga₂O₃crystal was established.In this way,the stress field distribution of the crystal at different cutting depths is analyzed,and the nucleation position and propagation direction of subsurface cracks in the crystal are predicted by Matlab.