ẢNH HƯỞNG CỦA CHẾ ĐỘ Ủ ĐẾN SỰ TIẾT PHA CỦA HỢP KIM ENTROPY CAO FeCoNiAl0,75Nb0,25=THE EFFECT OF ANNEALING REGIME ON THE PRECIPITATION OF FeCoNiAl0.75Nb0.25 HIGH ENTROPY ALLOY

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Tác giả: Minh Đức Lê, Hồng Hải Nguyễn, Mạnh Hùng Nguyễn, Thanh Hùng Nguyễn

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Journal of Science and Technique: Section on Physics and Chemical Engineering, 2024

Mô tả vật lý: tr.37

Bộ sưu tập: Metadata

ID: 483662

Thêm vào giỏ

Bài báo này nghiên cứu ảnh hưởng của chế độ ủ đến sự tiết pha của hợp kim entropy cao FeCoNiAl0,75Nb0,25. Cấu trúc vi mô sau đúc bao gồm các pha nhánh cây thô, to được thay thế bằng hình thái đẳng trục, và sự phân bố của pha giữa nhánh cây trở nên đồng đều hơn khi tăng thời gian và nhiệt độ ủ lên tới 825°C. Quá trình tiết pha bắt đầu ở 700°C trong 8 giờ, thời gian tiết pha được rút ngắn xuống 4 giờ khi tăng nhiệt độ ủ. Kích thước của pha này chỉ vài μm. Tỉ lệ pha tiết ra tăng và kích thước của pha nhánh cây giảm khi nhiệt độ ủ tiến tới 825°C, trong khi kích thước này tăng ở chế độ 925°C/16 giờ. Cấu trúc vi mô thô, pha tiết ra dần biến mất khi ủ ở 1000ºC. Độ cứng HV3 của hợp kim tăng theo thời gian khi nhiệt độ thấp hơn 825ºC và đạt giá trị cao nhất ~ 614 kg/mm2 ở 600ºC/24 giờ
giá trị này bắt đầu giảm ở chế độ 925°C/16 giờ. Trong khi đó, độ cứng giảm dần khi tăng thời gian ủ ở 1000°C. Có thể dự đoán là do sự thô hóa nhanh của pha nhánh cây, tỉ lệ pha tiết ra trong hợp kim giảm và xuất hiện hiện tượng chảy dẻo ở biên giới hạt.This paper investigates the effect of the annealing regime on the precipitation of FeCoNiAl0.75Nb0.25 high entropy alloy. The as-cast microstructure consists of coarse dendritic phases that are replaced by equiaxed morphology, and the distribution of the interdendritic phase becomes regularly better with increasing time and annealing temperature up to 825ºC. The precipitated process begins at 700ºC for 8 hours, shortening to 4 hours when the annealing temperature increases. The size of this phase is only a few μm. The fraction of the precipitated phase increases and the size of the dendritic phase is reduced as the annealing temperature is up to 825ºC, while this size rises in the 925ºC/16 hours regime. The microstructure is coarse, and the precipitated phase gradually disappears when the annealing is at 1000ºC. The HV3 hardness of the alloy increases with annealing time when the temperature is lower than 825ºC and reaches the highest value of ~ 614 kg/mm2 at 600ºC/ 24 hours
this value begins to decrease for the 925ºC/16 hours regime. Meanwhile, the hardness gradually decreases with increasing annealing time at 1000ºC. It can be expected due to the rapid coarsening of the dendritic phase, the decrease in the proportion of the precipitated phase in the alloy, and the appearance of plastic flow phenomena at grain boundaries.

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