open access publication

Article, 2022

Towards the additive manufacturing of Ni-Mn-Ga complex devices with magnetic field induced strain

Additive Manufacturing, ISSN 2214-8604, 2214-7810, Volume 49, Page 102485, 10.1016/j.addma.2021.102485

Contributors

Ituarte, Iñigo Flores 0000-0002-1940-7527 (Corresponding author) [1] [2] Nilsén, Frans 0000-0002-4952-5049 [3] [4] Nadimpalli, Venkata Karthik 0000-0002-8464-3577 [2] Salmi, Mika V J 0000-0002-7295-3551 [5] Lehtonen, Joonas 0000-0003-2052-5667 [5] Hannula, Simo-Pekka [5]

Affiliations

  1. [1] Tampere University
    2. [NORA names: Finland; Europe, EU; Nordic; OECD];
  2. [2] Technical University of Denmark
    3. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
  3. [3] Institute of Physics
    4. [NORA names: Czechia; Europe, EU; OECD];
  4. [4] Mechanical Engineering and Metals Industry Standardization in Finland (METSTA), Eteläranta 10, PL 10, 00131 Helsinki, Finland
    5. [NORA names: Finland; Europe, EU; Nordic; OECD];
  5. [5] Aalto University
    6. [NORA names: Finland; Europe, EU; Nordic; OECD]

Abstract

Laser powder bed fusion (L-PBF) is used to produce foam-like Ni-Mn-Ga with tailored microscale and mesoscale features. Ni50-Mn28.2-Ga21.8 (at%) powder was gas atomised and processed in an L-PBF system with a range of energy density from 26.24 and 44.90 J/mm3. We characterised microscale and mesoscale properties, such as the chemical composition, crystal structure, magnetisation measurements, density, and porosity measurements as a function of process parameters, in a systematic design of experiment. Preliminary research on macroscale properties included tensile testing and magnetic field induced strain (MFIS) measurements. Results show how controlling process parameters allows tailoring the Ni-Mn-Ga polycrystalline microstructure. Hence, obtaining twinned martensitic structures with a predominant orientation going across the visible grain boundaries. All the processed samples showed a 56 Am2/kg magnetisation level, close to Ni-Mn-Ga 10 M single crystals. Mesoscale results show a distinctive porosity pattern that is tailored by the process parameters and the laser scanning strategy. In contrast, macroscale mechanical tensile test results show a brittle fracture of Ni-Mn-Ga due to the high porosity with yield stress 2–3 times higher than shown in single crystals. In sum, we built geometrically complex demonstrators with (i) microscale twinned martensitic structures with a predominant orientation going across the visible grain boundaries and (ii) mesoscale tailored periodic porosity patterns created by modifying power, scanning speed, and scanning strategy systematically. L-PBF demonstrates great potential to produce foam-like polycrystalline Ni-Mn-Ga, reducing grain boundary constraints and thus the magnetic force needed for MFIS.

Keywords

Am2/kg, J/mm3, L-PBF, L-PBF systems, MFIS, Ni–Mn–Ga, bed fusion, boundaries, boundary constraints, brittle fracture, chemical, chemical composition, complex demonstratives, complex devices, composition, constraints, controlling process parameters, crystal, crystal structure, demonstration, density, design of experiments, devices, energy, energy density, experiments, features, force, function, function of process parameters, fusion, gas, geometrically, grain boundaries, grain boundary constraints, high porosity, laser, laser powder bed fusion, laser scanning strategy, levels, macroscale properties, magnetic force, magnetisation, magnetisation level, magnetisation measurements, manufacturing, martensitic structure, measurements, mesoscale, mesoscale features, mesoscale properties, mesoscale results, microstructure, orientation, parameters, patterns, polycrystalline Ni–Mn–Ga, polycrystalline microstructure, porosity, porosity measurements, porosity patterns, potential, powder bed fusion, power, predominant orientation, preliminary research, process, process parameters, properties, research, results, samples, scanning, scanning speed, scanning strategy, speed, strategies, stress 2, structure, system, systematic design, systematic design of experiments, tensile, tensile test results, tensile tests, test, test results, twinned martensitic structure, visible grain boundaries, yield

Funders

  • Ministry of Education Youth and Sports

Data Provider: Digital Science

LINKS
-

Matching Records in NORA

SUBJECTS
+

METRICS
+