Α2 Phase Research Articles

Microstructure evolution and enhanced mechanical properties of as-rolled TiB/(TA15-Si) composite via heat treatment

To improve the mechanical properties of the as-rolled composite under large rolling deformation, the effect of solid solution and aging on the microstructural characteristics and mechanical properties of the as-rolled TiB/(TA15-Si) composite was detailedly investigated. The solid solution temperatures of 1050 °C in the β-phase field and different aging temperatures of 550–750 °C were chosen to regulate the evolution of matrix and silicides. After solid solution treatment, the matrix transformed from elongated and kinkled lamella into acicular martensite microstructure. And the silicides completely redissolved into matrix and a uniform diffusion of Si atom was presented. Meanwhile, the aging temperature can obviously affect the evolution of martensite and silicides. As aging temperature increased, the martensite gradually decomposed into acicular α+β lamella (at 650–700 °C) and abnormal growth of α phase appeared (at 750 °C), which dominated the decreasing trend of microhardness and high-temperature strength. Besides, the silicides gradually precipitated along the prior β phase and TiB whiskers (at 600 °C) as well as α/β phase boundaries (at 650 °C). Eventually, 600 °C and 700 °C strengths of the as-rolled composite can be obviously improved by 39.7 % and 84.6 % after solid solution and aging processes. And the composite aged at 600 °C can obtain the highest 600 °C strength of 992 MPa, which is mainly attributed to martensite, precipitation of silicides and weak α2 phase.

Influence of Various Alloying Element Additions on Microstructure and Magnetic and Mechanical Properties and Corrosion Behavior of Cast Fe–Ga–Z Shape Memory Alloys

Fe–Ga alloys are attractive materials where high mechanical strength, toughness, ductility, and large low-field magnetostriction combine to give unique properties. Adding alloying elements is an effective method to further enhance these properties. In order to integrate these alloys into the operating environments, e.g., micro-robots and magnetic actuators, the corrosion behavior should be addressed. This work analyzed the microstructure, magnetization, hardness, and corrosion properties of Fe81Ga19−xZx (X = 5 at.% of Ni, Mn, or Ti, and 2 at.% Al; separately) alloys. X-ray diffraction (XRD), scanning electron microscope-electron (SEM), vibrating sample magnetometer (VSM), Vickers hardness (HV), and a potentiostat were used for characterization. XRD revealed that the prominent peak belongs to the bcc disorder A2 phase and a small peak for the cubic order L12 phase. Fe–Ga–Al alloy got the maximum Ms value, while Fe–Ga–Mn alloy gained the lowest one. However, the Mr and Hc properties for Fe–Ga alloy were distinctly improved by adding Al but slightly affected by doping Mn. Addition of Ti achieved the highest hardness, followed by Ni, Mn, and Al. The microstructure of the different alloys significantly influenced their corrosion behavior. Fe–Ga–Mn alloy with the fine globular grain structure showed the lowest corrosion rate (C R = 0.03 mm/year), whereas Fe–Ga–Al alloy with the coarse longitudinal grains exhibited the highest corrosion rate (C R = 0.19 mm/year).

Increasing ductility via Cu addition in AlxCrFeMnNi: Towards a scrap-based high entropy alloy

Alloys comprising common alloying elements are more amenable to accepting high fractions of scrap. The present study examines the effect of Cu and Al addition on common element containing multiple principal element alloy (CE-MPEA): AlxCuyCrFeMnNi (x = 0, 0.15, 0.3, 0.6, 0.9 and y = 0, 0.07, 0 = 0.14). Alloys were fabricated by arc casting. As expected, after quenching, the microstructures displayed FCC A1, Cr-rich BCC A2 and B2 precipitate phases in varying amounts. Adding small amounts of Cu to low and medium Al alloy groups increased the FCC phase fraction and refined the FCC grains. It is proposed that these microstructural changes account for the increased ductility seen to accompany Cu addition. A hybrid model was successfully employed to predict the hardness of the FCC phase. In contrast to high Cu-containing HEAs from prior studies, Cu additions in the studied alloys did not detrimentally affect the corrosion resistance in idealised polarization corrosion tests in salt solution. This can be ascribed to the absence of a Cu-rich FCC phase at the low Cu levels employed in the present work. The current alloys show promise as a base composition for further development into a tough fine-grained stainless alloy able to be produced using high fractions of scrap input.

Microstructure evolution and coarsening behavior of precipitated O phase in Ti–22Al–24Nb-0.5Mo (at. %) alloy during the heat treatment

Microstructure evolution and coarsening behavior of precipitated O phase were systematically investigated in this study, and the corresponding microstructures were characterized by scanning electron microscopy and transmission electron microscopy. The results showed that the original microstructure was composed of lath O phase, α2 phase and B2 matrix. The precipitated O phase presented different morphologies and sizes during heat treatment. With the increase of solution temperature and holding time, the O phase occurred coarsening, with a thickness ranging from 0.73 increased to 2.64 μm. But the volume fraction decreased from 57.65 to 18.40 %. During aging treatment, large amounts of fine secondary acicular O phase have precipitated from the matrix. As the aging temperature increases, the O phase underwent coarsening and the thickness increases from 0.70 to 1.40 μm. However, the aging temperature has little effect on the precipitation of acicular O phase, and the volume fraction decreases from 37.66 to 33.32 %. Research found that the small-sized O phase gradually dissolved in the matrix, while the large-sized O phase grew. This phenomenon can be explained by Ostwald ripening mechanism. The TEM analysis revealed that the O phase occurred separation, mainly due to the diffusion of solute atoms and the embedding of B2 matrix. Meanwhile, the O phase had been completed and segmented. The coarsening mechanism of the O phase was also explained by the boundary splitting mechanism and terminal migration mechanism.

The mechanical properties of TCP phase of rapidly cooled molybdenum

The rapidly-cooling of pure molybdenum (Mo) at 1010 Ks−1 and the uniaxial tensile of the solid at a strain rate of 2 × 10 s−1 were studied by molecular dynamics simulation; then the structure evolution was investigated in terms of pair distribution function and the largest standard cluster analysis. It is found that Mo melt was cooled into a complex crystal with multiple characteristic lengths. Further analysis revealed that it is a mixture topological close packing (TCP) crystal composed of the dominated A15 phase (Mo-A15) and the less Z phase, with H phase as twin grain boundary. The Phonon spectrum, potential energy, and cohesion energy revealed that Mo-A15 is stable slightly inferior to Mo-bcc. Compared to the prevailing bcc Mo, Mo-A15 holds much higher Young’s modulus, ultimate tensile strength, and Yield strength, being a representative material for barrier layer with high hardness.

Microstructure evolution and phase transformation mechanism of Ti–46Al–8Nb–2.5V alloy based on phase transformation geometric models

The microstructure of conventionally solidified and rapidly solidified Ti–46Al–8Nb-2.5V alloys was analyzed with phase transformation geometric models, revealing the phase transformation mechanisms. The β→α→γ phase transformation processes follow Burgers and Blackburn orientation relationships (ORs), respectively, from which the calculated transformation between the β/β0 and γ phases follow K–S OR. Whlie, the direct β/β0→γ phase transformation can be directly observed in the microstructure, which follows a variety of ORs, mainly following the K–S OR but also following the N–W or Bain ORs, most of which deviate from the strict ORs. In cases where N–W and Bain ORs are followed, there is a large dislocation spacing between the habit planes of the β/β0 and γ phases, resulting in low static energy at the interface and narrow elongated morphology of precipitated phases. Conversely, when following K–S OR for β/β0 → γ phase transformation, interfacial migration energy is relatively lower and grain precipitated phases is larger. The rapidly solidified microstructure of Ti–46Al–8Nb-2.5V alloy consists of the massive α2 phase, massive γ phase, and basket-weave β0 phase closely resembling those found in β-type titanium alloys. After annealing at service temperature, the rapidly solidified alloy forms a microstructure highly similar to that of conventionally solidified TiAl alloy. Various metastable phases, such as the Ti2Al, L12 and Ti1.4Al phases, precipitate in the blocky γ phase, which provides a theoretical basis for studying the phase transformations of TiAl alloys in service.

First-principles insights on the A15 phase in Ti-Se system

A pressure-composition phase diagram of Ti-Se system has been established after a comprehensive computational study at high pressure. As the pressure increases to 72 GPa, a new A15 Ti3Se structure is predicted and it can be stabilized dynamically at zero pressure. We further investigate the electronic and superconducting properties of A15 Ti3Se. Due to the significant contribution of transition metal d electrons at the Fermi level, the phonon properties of the Ti-lattice considerably enter into the calculation of electron-phonon interactions. The calculated robust superconducting critical temperature Tc (μ∗= 0.10-0.15) is 26-21.34 K under 80 GPa. Our results may provide theoretical guidance for the discovery of other titanides at high pressure, facilitating the exploration of A15 superconductors in the form of A3B.

The effect of Al addition on the microstructure, magnetostrictive and mechanical properties of Fe73Ga27 alloy

Fe-Ga alloy exhibits two magnetostrictive peaks when the Ga content (at%) is 19 and 27, respectively but most studies have focused on improving the performance of Fe81Ga19. In order to reduce the manufacturing cost of the alloys and achieve better mechanical properties, Al element is used to replace part of the Ga of Fe73Ga27 alloy in this experiment. So long as the magnetostrictive properties does not decrease significantly, which is in line with expectations from an engineering application perspective. Fe73Ga27−xAlx (x = 0,1,2,3,4,5) alloys were prepared by vacuum arc furnace and the effect of Al addition on the microstructure, magnetostrictive properties, and mechanical properties of the alloys is studied. The results show that the phase structure of alloys is chiefly composed of A2 phase and the metallographic structure of the alloys is comprised of equiaxed and columnar grains. The fracture morphology of the alloys is principally intergranular brittle fracture and cleavage fracture, and the reasons for the alloys fracture include the detachment of Fe and Al elements and the segregation of Fe, Ga, Al elements. Except for Fe73Ga27 alloy, the tensile strength, elongation, and Vickers hardness of the alloys are ameliorated when the content of Al added is equal to 4 at% while the parallel magnetostrictive strain(λ∥) of the alloy crested 81 ppm, which is 24.3% higher than Fe73Ga27.

Crack suppression in wire-arc directed energy deposition of a γ-TiAl alloy

It was a big challenge to effectively eliminate cracks in wire arc directed energy deposition of TiAl alloys. Crack-free γ-TiAl alloy deposition layers were fabricated by a combining technique of preheating and heat preservation. A coupled thermo-mechanical model was developed to calculate the thermal stress evolution in the deposited layer. A first-principle model was employed to calculate the free energy and ductility of the γ and α2 phases. Based on the numerical and microstructural analyses, the crack suppressing mechanism was revealed. The α2 phase had a higher residual stress state at the boundary, and was more stable and brittle than the γ phase. The cracks were suppressed by decreasing the thermal stresses and brittle α2 phase formation.

Improved corrosion resistance of laser melting deposited CoCrFeNi-series high-entropy alloys by Al addition

The microstructural evolution, pitting performance, and passive-film properties of AlxCoCrFeNi high-entropy alloys (HEAs) fabricated via laser melting deposition (LMD) were investigated using material characterization techniques and electrochemical measurements. The substrates of the LMD HEAs transform from a face-centred cubic (FCC) to a body-centred cubic (BCC) structure with increasing Al addition. The BCC-structured B2 and A2 phases precipitate in the HEA substrate when the Al content reaches 10 mol.%. Ternary-phase HEA with Al addition of 10 mol.% exhibits the best corrosion resistance, which is attributed to favourable modifications in the Cr2O3 content and passive-film thickness.

Improvement in compressive creep resistance of Ti-43.5Al–4Nb–1Mo-0.1B alloy via micro-alloying with C and Si

In the present work, the effects of the addition of C and Si on the compressive creep behavior of Ti-43.5Al–4Nb–1Mo-0.1B (TNM) alloy at 850 °C and 900 °C under 260 MPa were investigated. The results show that micro-alloying with C and Si can significantly strengthen the compressive creep resistance of TNM alloy. During compressive creep, obvious dynamic recrystallization occurs in TNM alloy, including major discontinuous dynamic recrystallization and minor continuous dynamic recrystallization. The development of dynamic recrystallization greatly softens the alloy, which leads to large creep deformation. Meanwhile, with the increase of creep strain, the bearing area increases and the actual stress decreases, which eventually results in the secondary creep behavior. In addition, the content of α2 phase increases during compressive creep, which can be attributed to two phase transformations. After adding C and Si, the B2 phase content is decreased and the lamellar colony size is increased, which contributes to the improvement of creep resistance. In addition, fine and dispersed Ti3AlC and Ti5Si3 particles precipitate in α2 lamellae during compressive creep, and maintain definite orientation relationships with α2 and γ phases. This will delay the decomposition of α2 lamellae and greatly improve the lamellar stability. Then, the excellent lamellar stability will inhibit the development of dynamic recrystallization, thus effectively reducing the creep rate.

The Role of Boron Addition on Solidification Behavior and Microstructural Evolution of a High Niobium-Containing TiAl Alloy

This work investigates the role of boron addition in the solidification behavior and microstructural evolution during the heat treatment process of Ti-46Al-8Nb-xB (x = 0.1, 0.7, 1.4, 2.5 at.%). The results show that the solid solution boron element prefers to occupy the interstitial vacancies of the α2 phase in the alloy. However, the solid solubility of the boron element in high Nb-containing TiAl alloys is extremely low. Therefore, it does not have a significant effect on the lattice distortion of α2 and γ phases in the alloy. When the boron content is added up to 0.1%, a B27-type TiB precipitated phase is produced in the alloy. The morphology of borides mostly shows short rod-like structures, and a few show long curved shapes. And the addition of boron refines both the alloy colony size and the lamellar structure. Furthermore, it is also found that boron addition weakens the casting texture of the alloy. After a solid solution and different time aging heat treatment process, the microstructure of different boron content alloys have experienced obvious coarsening phenomenon. However, the morphology of the boride is closely related to boron content and heat treatment.

Compressive creep behavior of high Nb containing TiAl alloy: Dynamic recrystallization and phase transformation

In this work, compressive creep behavior of Ti-43Al-6Nb-1Cr-1.5V alloy fabricated by vacuum induction skull melting technology was investigated at 800-950 °C. The results show that compressive creep behavior of this alloy strongly depends on temperature. At 800 °C and 850 °C, this alloy exhibits conventional three-stage creep characteristics with a well-defined steady-state creep stage, and creep strain is small. However, at 900 °C and 950 °C, this alloy exhibits unconventional creep characteristics, and creep strain increases sharply. Microstructure observation proves that this is mainly due to the occurrence of dynamic recrystallization (DRX). During creep, continuous dynamic recrystallization and discontinuous dynamic recrystallization appear simultaneously, but the latter is more significant. At 800 °C and 850 °C, creep deformation mainly depends on dislocation motion, while at 900 °C and 950 °C, DRX also greatly contributes to creep deformation. During creep, recrystallized grains preferentially form at β-segregation and α-segregation, and rising temperature from 850 °C to 900 °C facilitates the sharp increase of DRX fraction. The occurrence of DRX reduces dislocation density, which greatly softens the alloy. Besides, more α2 grains generate at γ grain boundary and grain boundary/twin intersection during creep, and maintain Blackburn orientation relationship with γ grains. This is the result of stress-induced γ→α2 phase transformation.

Cu-Mn-Ga-based full superelasticity single crystals with low stress hysteresis and high critical stress for inducing martensite

In this study, novel Cu-Mn-Ga-based (Cu-13Mn-6Ga-8Al-xMo, x = 0.5, 0.8, 1.0, wt. %) full superelasticity single crystals with great combination properties of low stress hysteresis, high critical stress, and full superelasticity were prepared for the first time. The results show that these single crystals consist of L21 austenite and A2(Mo) phase before and after annealing. The A2(Mo) phase increases with the increment of Mo content. Three single crystals with orientations close to [314], [415], and [236] all exhibit full superelasticity while applying large pre-strains, even being up to 10 % in Cu-13Mn-6Ga-8Al-1.0Mo single crystal. More importantly, the superelasticity behaviors show high critical stress for inducing martensite (up to 723 MPa in Cu-13Mn-6Ga-8Al-1.0Mo single crystal) and low stress hysteresis (about 30 ∼ 60 MPa). From the point of strength and functional characteristics, the Cu-13Mn-6Ga-8Al-xMo single crystals can be used as a new driving material.

Breaking the high-temperature strength-ductility trade-off in TiAl alloys through microstructural optimization

Designing a novel microstructure with higher strength-ductility than lamellar microstructure (LM), which has been considered the most valuable engineering application in the service temperature range, is desired for lightweight TiAl alloys. Our prior publication reported a three-phase tri-modal (T-T) structure for Ti-43.5Al-4Nb-1Mo-0.1B(.at%) with superior mechanical properties than LM at room temperature (Ref: Acta Mater. 225 (2022) 117,585). However, its strength-ductility at working temperature has yet to be fully exploited. This work fills the much-needed gap. The qualitative and quantitative optimizations indicate that the T-T structure's yield strength increases first and then decreases with increasing pearlitic-like microstructure (PM, which consist of three-phase (α2, γ and βo phase) with clear orientation relationships that form in a lamellar/cellular manner) content while the ductility keeps rising. When the T-T structure contains ∼20 % PMs, it exhibits a yield strength about 130MPa higher than LM coupling with doubled ductility at 750 °C. PMs can induce a prominent twinning induced plasticity and dislocation jog dragging (TWIP&DJD) effect, resulting in better strength-ductility below 700°C; above this temperature, the TWIP&DJD effect significantly plasticizes the alloys. The higher strength of the T-T structure at 750 °C is caused by hetero-deformation-induced strengthening between LMs and PMs, which cannot be offset by the plasticizing caused by PM when the volume fraction of PMs is less than 50 %. This study demonstrates that introducing an appropriate amount of plasticizing structures (similar to PM) with excellent work hardening capacity is a promising strategy for enhancing the strength-ductility synergy of TiAl and possibly other brittle materials.

Microstructure Evolution of the Ti-46Al-8Nb-2.5V Alloy during Hot Compression and Subsequent Annealing at 900 °C.

TiAl alloys are high-temperature structural materials with excellent comprehensive properties, and their ideal service temperature range is about 700-950 °C. High-Nb containing the Ti-46Al-8Nb-2.5V alloy was subjected to hot compression and subsequent annealing at 900 °C. During hot compression, work-hardening and strain-softening occurred. The peak stresses during compression are positively correlated with the compressive strain rates and negatively correlated with the compression temperatures. The α2 phase exhibited a typical (0001)α2 basal plane texture after hot compression, while the β0 and γ phases did not show a typical strong texture. Subsequent annealing at 900 °C of the hot-compressed samples resulted in significant phase transformations, specifically the α2 → γ and β0 → γ phase transformations. After 30 min of annealing, the volume fraction of the α2 phase decreased from 39.0% to 4.6%. The microstructure characteristics and phase fraction after 60 min of annealing were similar to those after 30 min. According to the calculation of Miller indexes and texture evolution during annealing, the α2 → γ phase transformation did not follow the Blackburn orientation relationship. Multiple crystal-oriented α2 phases with nanoscale widths (20~100 nm) precipitate within the γ phase during the annealing process, which means the occurrence of γ → α2 phase transformation. Still, the γ → α2 phase transformation follows the Blackburn orientation relationship.

Tracking maze-like hierarchical phase separation behavior in a Fe-Si-V alloy

Optimizing the properties of next-generation high-temperature and corrosion-resistant alloys is rooted in balancing structure-property relationships and phase chemistry. Here, we implement a complementary approach based on transmission electron microscopy (TEM) and atom probe tomography (APT) to ascertain aspects of hierarchical phase separation behavior, by understanding the microstructural evolution and the three-dimensional (3D) nanochemistry of a single crystal Fe79.5Si15.5V5.0 (at%) alloy. A maze-like hierarchical microstructure forms, in which a complex network of metastable disordered α plates (A2 phase) emerges within ordered α1 precipitates (D03 phase). The supersaturation in α1 (D03) precipitates with Fe and V drives the formation of α (A2) plates. The morphology of α (A2) plates is discussed concerning crystal structure, lattice misfit, and elastic strain. Phase compositions and a ternary phase diagram aid the thermodynamic assessment of the hierarchical phase separation mechanism via the Gibbs energy of mixing. A perspective on the stabilization of hierarchical microstructures beyond Fe79.5Si15.5V5.0 is elaborated by comparing hierarchical alloys. We find that the ratio of elastic anisotropy (Zener ratio) serves as a predictor of the hierarchical particles’ morphology. We suggest that the strengthening effect of hierarchical microstructures can be harnessed by improving the temporal and thermal stability of hierarchical particles. This can be achieved through phase-targeted alloying aiming at the hierarchical particles phase by considering the constituents partitioning behavior. Beyond Fe79.5Si15.5V5.0, our results demonstrate a potential pathway for improving the properties of high-temperature structural materials.

Manipulate A2/B2 Structures in AlCrFexNi Alloys for Improved Mechanical Properties and Wear Resistance

Precipitation strengthening of body-center cubic (A2) alloys via ordered B2 nanoprecipitates is expected to achieve a desirable combination of strength and ductility. In this work, the A2/B2 configuration is manipulated by adjusting Fe content in medium-entropy AlCrFexNi (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) alloys fabricated via arc-melting for improved mechanical properties and wear resistance. As Fe content increases, the fraction of A2 phase increases, and A2 nanoprecipitates in the B2 matrix change to a weave-like A2/B2 structure. Continuously increasing Fe content leads to a mixture of BMAP (B2 matrix with A2 precipitates) and AMBP (A2 matrix with B2 precipitates), and finally to a complete AMBP structure. The yield strength decreases and fracture strain increases with increasing Fe content except x = 0. The alloy of x = 0 displays slightly higher hardness because of its relatively brittle B2 matrix. Cracks tend to propagate along A2/B2 interfaces. AMBP structure exhibits greater toughness than the BMAP structure. The alloy of x = 0 displays the second-greatest wear volume loss due to its relatively brittle B2 matrix. When Fe is added, the wear volume loss decreases considerably but shows a trend of an upward parabola with respect to the Fe content. After achieving the highest volume loss at x = 1.5 with a mixture of AMBP and BMAP, the volume loss decreases again. A completely uniform AMBP structure at x = 3.0 shows the least volume loss.

Microstructure evolution and mechanical properties of pulse high current diffusion bonding γ-TiAl alloy to Ti2AlNb alloy

The development of lightweight high-temperature materials and their processing methods are receiving increasing attention as the need for improved performance and energy efficiency in aero-engines increase. In this study, the γ-TiAl alloy was successfully soundly bonded to Ti2AlNb alloy by pulsed high current (PHC) diffusion welding. The effect of different high level (HL)/low level (LL) of composite pulse current on the microstructure and mechanical properties of the joints have been studied. The representative interface microstructure of PHC-950 °C TiAl/Ti2AlNb joint was γ-TiAl substrate/diffusion bonding zone/Ti2AlNb impacted zone/Ti2AlNb substrate. The diffusion bonding zone was composed of continuous equiaxed α2 grains and a small amount of B2 and O phases. The α2 phase in the diffusion bonding zone was mainly transformed from the γ phase in γ-TiAl substrate and the B2 and O phase in Ti2AlNb substrate. The composite pulse current has a significant promoting effect on the diffusion of elements and joint formation. The diffusion coefficients of DAl and DNb in hot-pressing (HP, without current effect) diffusion welding joint at interface were 2 × 10−14 m2/s and 0.92 × 10−14 m2/s, respectively. In the representative PHC-950 °C joint with HL/LL = 12/2 cycles (single cycle duration 3.3 ms), diffusion coefficients of DAl-12/2, DNb-12/2 at interface were 19.62 × 10−14 m2/s, 13.34 × 10−14 m2/s, respectively. Increasing the duration of LL would weaken the current effect. The current waveform parameters were tuned to HL/LL = 12/4 and 12/6 cycles, the diffusion coefficients of DAl-12/4, DNb-12/4DAl-12/6 and DNb-12/6 were reduced to 15.69 × 10−14 m2/s, 12.49 × 10−14 m2/s, 15.31 × 10−14 m2/s and 10.99 × 10−14 m2/s, respectively. The PHC-950 °C joints have the highest shear strength of 257.3 MPa at HL/LL = 12/2 cycles, reaching 83.3% of the base material strength. The HP-950 °C TiAl/Ti2AlNb joint has a shear strength of 230.5 MPa, reaching 74.6% of the base material strength. The shear strength of PHC-950 °C joints at HL/LL = 12/4 and 12/6 reduced to 205.3 MPa, 195.8 MPa due to insufficient element diffusion and damages the bonding quality. This work provides a strategy that contributes to reduce the thermal damage of base metal and improve the joint forming efficiency.

S2-5 Physical Literacy in Austria: development of the Perceived Physical Literacy Questionnaire (PPLQ) for the adult population

Abstract Purpose Physical Literacy (PL) is a relatively new concept in Austria. However, PL research in Austria is currently centered around one research group and has focused exclusively on adults, a cohort which has been largely overlooked by the PL community so far. Recent projects included an intervention to increase PL in physically inactive adults and the development of the Perceived Physical Literacy Questionnaire (PPLQ). The PPLQ is a comprehensive but easy-to-use and easy-to-understand PL questionnaire for adults in German language. We describe the development process of this questionnaire in the following. Methods The process subsumes several phases with the involvement of experts to ensure high content validity. In phase 1, a PL questionnaire was taken from our previous pilot studies for further improvement. This instrument was not yet validated, but already consisted in large part of established questionnaire (subscales) for six PL domains (motivation, confidence, physical competence, knowledge, understanding, and physical activity behavior). In phase 2, the revised 51-item instrument was tested in an online-survey (N = 506) and a shortened version was developed using exploratory factor analyses. The remaining 31 items were inspected using cognitive interviews (phase 3) and an external comprehensibility check to ensure language level A2 (phase 4). Subsequent results belong to phase 5, in which reliability as well as factorial and convergent validity were tested in another sample of 417 adults. Results The assumed 31-item model revealed misfits on global and local level and was modified based on expert opinions and statistical considerations but remained with six PL dimensions. After reducing the complexity of the model, we found empirical support for a theory-compatible 24-item version. The global model-fit of the final model was acceptable with minor misfits at item level. Internal consistency (omega) and convergent validity results were satisfactory. Conclusion The PPLQ is the first PL assessment instrument for a broad adult population that incorporates the holistic nature of the concept. However, further studies should attempt to improve the identified minor weaknesses and apply it in different language versions. These initial results are promising for the application in research as well as practice. Support/Funding Source No specific funding.