Investigations on the crystallographic stacking disordering and properties of novel Ga-containing in-plane chemically ordered (Cr2/3R1/3)2GaC (R=Y, Tb - Lu) i-MAX phases

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY Acta Materialia Pub Date : 2024-07-22 DOI:10.1016/j.actamat.2024.120213

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Abstract

Eight novel transition metal carbides, nanolaminated (Cr_2/3R_1/3)₂GaC (R=Y, Tb, Dy, Ho, Er, Tm, Yb and Lu) with R in-plane chemical ordered occupation, have been synthesized with mainly Cmcm orthorhombic structure and monotonously decreased lattice parameters due to lanthanide contraction. Stacking disorderings and high-density slidings within c plane have been observed. Two characteristic in-plane sliding, along [100] or [ $\bar{1} 30$ ]_o directions have been analyzed with former one leading into the structural evolution between Cmcm and C2/c symmetry. Such an atomic scale co-existence of Cmcm and C2/c structures is explained by more negative charge for Ga and anisotropic bonding with Ga compared with A=Al case. Thus, the Vickers hardness, fracture strength and increased wear depth are reduced in representative (Cr_2/3Lu_1/3)₂GaC i-MAX bulk compared with the (Cr_2/3Lu_1/3)₂AlC counterpart.

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新型含镓平面内化学有序 (Cr2/3R1/3)2GaC (R = Y, Tb - Lu) i-MAX 相的晶体学堆叠无序和性质研究

我们合成了八种新型过渡金属碳化物，即具有面内化学有序占位的纳米层状（Cr）GaC（= Y、Tb、Dy、Ho、Er、Tm、Yb 和 Lu），它们主要呈正菱形结构，由于镧系元素收缩，晶格参数单调降低。在平面内观察到堆叠无序和高密度滑动。我们分析了沿[100]或[]方向的两种特征性平面内滑动，前者导致了对称性和对称性之间的结构演变。与 A = Al 的情况相比，Ga 带有更多的负电荷以及与 Ga 的各向异性结合可以解释这种原子尺度的和结构共存现象。因此，与(Cr)AlC 相比，(Cr)GaC -MAX 块体的维氏硬度、断裂强度和磨损深度都有所降低。

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来源期刊

Acta Materialia 工程技术-材料科学：综合

CiteScore

16.10

自引率

8.50%

发文量

801

审稿时长

53 days

期刊介绍： Acta Materialia serves as a platform for publishing full-length, original papers and commissioned overviews that contribute to a profound understanding of the correlation between the processing, structure, and properties of inorganic materials. The journal seeks papers with high impact potential or those that significantly propel the field forward. The scope includes the atomic and molecular arrangements, chemical and electronic structures, and microstructure of materials, focusing on their mechanical or functional behavior across all length scales, including nanostructures.