Alloying and microstructural changes in platinum–titanium milled and annealed powders
- 1. Element Six Production Ltd, Diamond Research Laboratory, 1 Debid road, Nuffield, PO Box 561, Springs 1559 (South Africa)
- 2. Council for Scientific and Industrial Research, CSIR, Metals and Metals Processes, Lynnwood Manor, P.O. Box 395, Pretoria 0001 (South Africa)
- 3. National Institute of Materials Science, NIMS, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan)
Description
Graphical abstract: (a) SE-SEM micrographs of PtTi martensite formed in powder milled for short time annealed at 1500 °C and quenched in helium gas flow (b) BSE-SEM of structure formed after slow cooling. Highlights: ► A disordered metastable FCC Pt(Ti) solid solution was formed after longer milling period. ► HCP Ti crystals were first deformed and then the atoms were dissolved in strained FCC Pt lattices. ► Longer milling time suppressed the occurrence of martensitic transformation after annealing. ► Martensite phase was formed in products that went through a short milling time then annealed and quenched. ► The width of the martensite features formed was smaller at higher cooling rates. - Abstract: Equiatomic platinum–titanium powder mixtures were processed by high energy ball milling under argon atmosphere and sintered under vacuum. Evolution of the crystal structures and microstructures of the products formed were investigated by XRD and SEM techniques, respectively. The HCP crystals of Ti were first deformed and then a disordered metastable FCC Pt(Ti) solid solution was formed during milling due to semi-coherency of FCC lattices. A nanostructured Pt(Ti) product was formed after long milling time, which contained 44–47 at.% Ti and 53–56 at.% Pt. An ordered PtTi intermetallic was formed by annealing the metastable Pt(Ti) at temperature above 1300 °C. The crystal structure and microstructure of the TiPt phase depended on the milling time, annealing temperature and the cooling rate. The B19 PtTi plate martensite was formed after annealing at 1500 °C and quenching at a cooling rate of 23 °C/min to 200 °C/min for short time milled products. The width of martensite features was smaller at high cooling rate. In PtTi products milled for longer time, no martensitic transformation was observed on cooling the annealed samples. Small amounts of Pt5Ti3 were formed in the powders milled for 16 h or more, followed by annealing at 1500 °C and furnace cooling at ∼2 °C/min.
Availability note (English)
Available from http://dx.doi.org/10.1016/j.jallcom.2012.01.149Additional details
Identifiers
- DOI
- 10.1016/j.jallcom.2012.01.149;
- PII
- S0925-8388(12)00235-6;
Publishing Information
- Journal Title
- Journal of Alloys and Compounds
- Journal Volume
- 523
- Journal Page Range
- p. 167-175
- ISSN
- 0925-8388
- CODEN
- JALCEU
INIS
- Country of Publication
- Netherlands
- Country of Input or Organization
- International Atomic Energy Agency (IAEA)
- INIS RN
- 43103010
- Subject category
- S36: MATERIALS SCIENCE;
- Descriptors DEI
- ANNEALING; ARGON; CRYSTALS; FCC LATTICES; GAS FLOW; HELIUM; MARTENSITE; MICROSTRUCTURE; MILLING; NANOSTRUCTURES; PHASE TRANSFORMATIONS; PLATINUM; POWDERS; QUENCHING; SCANNING ELECTRON MICROSCOPY; SOLID SOLUTIONS; TITANIUM; X-RAY DIFFRACTION
- Descriptors DEC
- ALLOYS; CARBON ADDITIONS; COHERENT SCATTERING; CRYSTAL LATTICES; CRYSTAL STRUCTURE; CUBIC LATTICES; DIFFRACTION; DISPERSIONS; ELECTRON MICROSCOPY; ELEMENTS; FLUID FLOW; FLUIDS; GASES; HEAT TREATMENTS; HOMOGENEOUS MIXTURES; IRON ALLOYS; MACHINING; METALS; MICROSCOPY; MIXTURES; NONMETALS; PLATINUM METALS; RARE GASES; SCATTERING; SOLUTIONS; TRANSITION ELEMENT ALLOYS; TRANSITION ELEMENTS
Optional Information
- Copyright
- Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.