中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 29 No. 10 October 2019 |
（1. Institute of Materials Processing and Intelligent Manufacturing, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China;
2. Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001, China）
Abstract:To clarify phase transformation evolution of Nb-doped Ni-Mn-Ga bulk alloys after aging and ball milling, the microstructure and phase transformation of the aged and ball-milled dual-phase Nb-doped Ni-Mn-Ga alloys were investigated by SEM, EDS, XRD, DSC and susceptibility measurements. The as-cast alloys were mainly composed of the second phase with layer-shape and presented a reduced martensitic transformation with increasing the second phase content. The second phase transformed from layer-shape to dense bar-shape and the martensitic transformation was enhanced after being quenched at 1173 K. After aging at 673 and 873 K, the 3% Nb alloy with less second phase exhibited a single-step phase transformation, whereas the 6% Nb and 9% Nb alloys with more second phase exhibited a two-step martensitic transformation and Curie transition. The martensitic transformation and Curie transition of the as-milled dual-phase particles disappeared and were retrieved after annealing at 1073 K due to the recovery of high ordered structure of the matrix.
Key words: Ni-Mn-Ga-Nb alloy; thermal treatment; ball milling; microstructure; phase transformation
