The martensites in steel T8A containing 0.8 pct C were examined by light microscope and TEM after martensitic austemper. There were boundary plate martensite, 12251 , butterfly martensite, { 2251, plate martensite, { 1 1 1 ], plate martensite, { 111 ], butterfly martensite and ( Ill], lath martensite observed in the steel. With the decrease of transformation temperature, the morphologies of the martensites formed changed from butterfly or plate to lath, the substructures from partial twin to dislocation and the habit planes from 12251, to ill1 1 ,. All these changes were controlled by the relief of elastic strain energy in the parent phase austenite. In a microregion of lath martensite, the martensites nucleate on two independent { 1111, planes respectively, and were formed in the way of filling in. The morphology of 1 1111, plate martensite found in this paper was similiar to that of thin plate martensite, bu it was mainly parallel and its substructure was partial twins.

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Abstract.Compact deformation -induced martensite found in Fe -25Ni -0.66C alloys has been studied by using optical, electron and scanning electron microscopy. The compact martensite consists of a large number of martensites with different variants connected closely to form large bulk in which almost no residual austenite remains. Its formation process is by further growth of thin plates to form lenticular plates and possible crossing and coalesence to form bulky martensite. These growth and coalesence are through martensitic twinning or twinning domains during deformation which leads to various interactions between the plates including cross, insert, coalescence and conversion. The substructure of the martensite is a crisscross twinning net. The corresponding deformation modes of the austenite are also studied.

Against the background of a high-quality development philosophy, the realization of the coordinated development of the economy, environment, and resources is particularly important. This study adopts the super-efficiency slacks-based measure (SBM) model to evaluate the eco-efficiency of 208 cities in 19 urban agglomerations in China from 2006 to 2020, and the kernel density estimation and spatial econometric specifications are combined to reveal the spatial–temporal evolution. Finally, Tobit regression is used to analyze the driving factors of the eco-efficiency of urban agglomerations in China. The main results can be summarized as follows: (1) The eco-efficiency of Chinese urban agglomerations is generally low, and the differences in eco-efficiency between urban agglomerations are obvious, with different trends of change. (2) In terms of the time series, the sample period shows a “steadily rising” trend followed by a “fluctuating downward” trend. From the results of the kernel density estimation, the internal difference in the overall eco-efficiency of urban agglomerations shows the trend of a small decline followed by a gradual increase. (3) From the spatial point of view, the eco-efficiency of urban agglomerations decreased from the coast to the inland areas, and there was a “cluster effect”. The overall eco-efficiency of urban agglomerations shows a trend of spatial aggregation. (4) From the perspective of influencing factors, fiscal expenditure, opening-up level, and population density have a significant negative correlation with the eco-efficiency of urban agglomerations, while science and technology investment, industrial structure, and urbanization level have a significant positive correlation with the eco-efficiency of urban agglomerations. The research in this paper provides guidance for the coordinated development of urban agglomerations and the formulation of environmental policies.