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Effect of Ball on SPS Characteristics of Ti-Al-Nd Powders Prepared by High Energy Ball Milling

Lee Hyunseung, Rhee Hoseong, Lee Sangsoo, Chang Si Young

Archives of Metallurgy and Materials

2023

Vol. 68, iss. 1

81--84

The effects of different types of balls on spark plasma sintering (SPS) characteristics of high energy ball milled Ti-48wt% Al-4wt% Nd powders were investigated. After ball milling with STS balls and zirconia balls at 800 rpm for 3 h in argon atmosphere, both powders showed shape factors of about 0.8, but their average powder sizes differed respectively at approximately 11 µm and 5 µm. From XRD results, only the peaks of pure Ti, Al and Nd were detected in both powders. The obtained Ti-Al-Nd powders were consolidated by SPS technique at 1373 K for 15 min under a pressure of 50 MPa in vacuum, resulting in high density over 99%. EDS and XRD analyses indicated the formation of binary phases such as TiAl3, TiAl, Ti3Al5, and NdAl3 after SPS in both cases of STS and zirconia balls, while the ternary Ti-Al-Nd phase was detected only in the case of zirconia balls. The size of second phases was slightly smaller in the case of zirconia balls. The microhardness of the sample was 790 Hv with zirconia balls and 540 Hv with STS balls.

Microstructural Characteristics of Ti-Al-Dy Alloy Produced by High Energy Ball Milling

Kim Yuri, Rhee Hoseong, Chang Si Young

Archives of Metallurgy and Materials

2021

Vol. 66, iss. 3

789--783

In this study, the alloying of Ti, Al and Dy powders by high energy ball milling, and the spark plasma sintering (SPS) characteristics of as milled powders have been investigated based on the observation of microstructure. Pure Ti, 6wt% Al and 4wt% Dy powders were mixed and milled with zirconia balls at 600 ~ 1000 rpm for 3h in an Ar gas. The initial sizes of Ti, Al and Dy powders were approximately 20, 40, and 200 μm, respectively. With increasing the milling speed from 600 to 1000 rpm, the size of mixing powders reduced from 120 to 15 μm. On the other hand, from XRD results of powders milled at higher speeds than 700rpm, the peaks of Ti3Al and AlDy phases were identified, indicating the successful alloying. Therefore, the powders milled at 800 rpm have been employed for the SPS under the applied pressure of 50 MPa at 1373K for 15 min. In the SPSed sample, the Al3Dy and two ternary Ti-Al-Dy phases were newly detected, while the peak of AlDy phase disappeared. The SPSed Ti-6Al-4Dy alloy revealed high relative density and micro-hardness of approximately 99% and 950Hv, respectively.