In this paper, we present the results of studying magnetic properties and magnetocaloric effect of Fe90-xPrxZr10 (x = 1, 2 and 3) rapidly quenched alloys. The alloy ribbons with thickness of about 15 µm were prepared by melt-spinning method on a single roller system. X-ray diffraction patterns of the ribbons manifest their almost amorphous structure. Thermomagnetization measurements show that the Curie temperature of the alloys can be controlled to be near room temperature by changing concentration of Pr (x). | Magnetic properties and magnetocaloric effect of Fe90-xPrxZr10 rapidly quenched alloys Vietnam Journal of Science and Technology 56 (1A) (2018) 59-64 MAGNETIC PROPERTIES AND MAGNETOCALORIC EFFECT OF Fe90-xPrxZr10 RAPIDLY QUENCHED ALLOYS Nguyen Hoang Ha1, 2, *, Nguyen Hai Yen2,3, Pham Thi Thanh2, 3, Dinh Chi Linh2, Nguyen Mau Lam4, Nguyen Le Thi1, 2, Nguyen Manh An1, Nguyen Huy Dan2, 3 1 Hong Duc University, 565 Quang Trung, Dong Ve, Thanh Hoa, Viet Nam 2 Institute of Science and Technology, VAST, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Viet Nam 3 Institute of Materials Science, VAST, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Viet Nam 4 Hanoi Pedagogical University , 32 Nguyen Van Linh, Phuc Yen, Vinh Phuc, Viet Nam * Email: nguyenhoangha@ Received: 15 August 2017; Accepted for publication: 20 February 2018 ABSTRACT In this paper, we present the results of studying magnetic properties and magnetocaloric effect of Fe90-xPrxZr10 (x = 1, 2 and 3) rapidly quenched alloys. The alloy ribbons with thickness of about 15 µm were prepared by melt-spinning method on a single roller system. X-ray diffraction patterns of the ribbons manifest their almost amorphous structure. Thermomagnetization measurements show that the Curie temperature of the alloys can be controlled to be near room temperature by changing concentration of Pr (x). When the concentration of Pr is increased, saturation magnetization of the alloys increased from 48 emu/g (with x = 1) to emu/g (with x = 2). All the ribbons reveal soft magnetic behavior with low coercive force (Hc < 42 Oe). The magnetic entropy change of the alloys, |∆Sm|max > in magnetic field change H = 12 kOe, shows large magnetocaloric effect at phase transition temperature. On the other hand, the working temperature range is quite large ( FWHM ~ 70 K) revealing an application potential in magnetic refrigeration technology of these .