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Statement of problem: Changing the internal design of a metal framework may decrease the manufacturing time, the weight of the restoration, and the amount of alloy powder used, as well as simplify the fabrication process. Purpose: The purpose of this in vitro study was to evaluate the effect of framework internal design changes on the mechanical properties of cobalt-chromium (Co-Cr) specimens manufactured by using direct metal laser sintering (DMLS). Material and methods: Dumbbell-shaped test specimens were designed as per the International Organization for Standardization (ISO) 22674(E) standard by using a 3-dimensional software program. A total of 70 dumbbell-shaped specimens were prepared by using Co-Cr alloy powder and DMLS (n=10). The control group specimens were solid with the internal completely filled. For the test groups, the internal design of the dumbbell-shaped specimens was modified. Leaving the outer shell thickness of the specimens at 0.5 mm for all test groups, 6 different internal designs were created, and the specimens were weighed. The tensile strength test was used to evaluate the mean peak strength, elastic modulus, and percentage elongation of the specimens. One-way ANOVA followed by the Dunnett T3 test was used for statistical analysis (α=.05). Results: A statistically significant difference was found among the groups in terms of bar weight and peak strength (P.05). Conclusions: Decreasing the weight of the frameworks by changing the internal design of the specimens also decreased the peak strength. However, it did not affect the elastic modulus or the percentage of elongation.

An AZ91–0.9Ca–0.6Y–0.5 MM (AZXWMM91100) alloy, which has higher corrosion resistance, ignition resistance, and extrudability than a commercial AZ91 alloy, has been developed recently. In this study, the AZXWMM91100 alloy is extruded at various temperatures (300–400 °C) and ram speeds (1–14.5 mm/s), and the cracking behaviors, microstructure, and tensile properties of the extruded materials are systematically analyzed. On the basis of the pressure limit and surface and internal cracking limit, the extrusion limit diagram providing a safe extrusion processing zone is established. All of the materials extruded at temperatures and speeds within the safe extrusion processing zone have high surface quality and moderate tensile ductility with an elongation higher than 10%. Moreover, they have a fully recrystallized grain structure and contain undissolved particle stringers arranged parallel to the extrusion direction. The grain size of the extruded material does not show any relationship with the Zener–Hollomon parameter (Z). However, the yield strength (YS) of the extruded material is inversely proportional to the logarithm of the Z value, and their relationship is expressed as YS = −31.2•log(Z) + 536. These findings may broaden the understanding of the AZXWMM91100 alloy with excellent chemical and physical properties and provide valuable information for the development of high-performance extruded Mg products using this alloy.

Statement of problem The climate of tropical Southeast Asia includes high humidity and ultraviolet radiation that reduce the lifespan of silicone prostheses by inducing changes in their mechanical properties and color stability. Studies on the surface roughness (SR) and mechanical properties of different silicone elastomers (SEs) subjected to the natural tropical weather of Southeast Asia are lacking. Purpose The purpose of this in vitro study was to evaluate the SR, tensile strength (TS), and percentage elongation (% E) of different SEs subjected to outdoor weathering in the Malaysian climate. Material and methods Type-II dumbbell-shaped specimens (N-120) (nonweathered=15, weathered=15) were made from 3 room-temperature vulcanized (A-2000, A-2006, and A-103) and 1 heat-temperature vulcanized (M-511) silicone (Factor II). For 6 months, weathered specimens were subjected to outdoor weathering inside a custom exposure rack. Simultaneously, the nonweathered specimens were kept in a dehumidifier. Subsequently, the SR was measured with a profilometer; TS and % E were measured by using a universal testing machine. Two-way ANOVA was used to compare the means of the tested properties of the nonweathered and weathered specimens, and pairwise comparison was carried out between the silicones (α=.05). Results After outdoor weathering, the SR, TS, and % E were adversely affected by weathering in the Malaysian environment. Among the silicone materials, A-2000 showed the least TS changes (2.51 MPa), while A-2006 demonstrated significant changes in percentage elongation after outdoor weathering (266.5%). M-511 exhibited the highest mean value (2.50 μm) for SR changes. In addition, A-103 SE showed statistically significant differences in most pairwise comparisons for all 3 dependent variables. Conclusions Based on the evaluation of mechanical properties, A-103 can be suggested as a suitable silicone for maxillofacial prostheses fabricated for tropical climates. However, A-2000 can be a suitable alternative, although significant changes to surface roughness were detected after outdoor weathering.

The effects of hydride amount (20–850 wppm), orientation (circumferential and radial), and temperature (room temperature, 100 °C, 200 °C) on the axial mechanical properties of Zircaloy-4 cladding were comprehensively examined. The fraction of radial hydride fraction in the cladding was quantified using PROPHET, an in-house radial hydride fraction analysis code. Uniaxial tensile tests (UTTs) were conducted at various temperatures to obtain the axial mechanical properties. Hydride orientation has a limited effect on the axial mechanical behavior of hydrided Zircaloy-4 cladding. Ultimate tensile stress (UTS) and associated uniform elongation demonstrated limited sensitivity to hydride content under UTT. Statistical uncertainty of UTS was found small, supporting the deterministic approach for the load-failure analysis of hydrided Zircaloy-4 cladding. These properties notably decrease with increasing temperature in the tested range. The dependence of yield strength on hydrogen content differed from temperature to temperature. The ductility-related parameters, such as total elongation, strain energy density (SED), and offset strain decrease with increasing hydride contents. The abrupt loss of ductility in UTT was found at ∼700 wppm. Demonstrating a strong correlation between total elongation and offset strain, SED can be used as a comprehensive measure of ductility of hydrided zirconium alloy.

For additive manufactured aluminum alloys, the inferior mechanical properties along the building direction have been a serious weakness. In this study, an optimized heat treatment was developed as a simple and effective solution. The effects of direct aging on microstructure and mechanical properties along the building direction of AlSi10Mg samples produced via selective laser melting (SLM) were investigated. The results showed that, compared with the conventional heat treatment at elevated temperatures, direct aging at temperatures of 130–190 °C could retain the fine grain microstructure of SLM samples and promote further precipitation of Si phase, however, the growth of pores occurred during direct aging. With increasing aging temperature, while finer cell structures were obtained, more and larger pores were developed, resulting in decreased density of the samples. Two types of pore formation mechanisms were identified. Considering the balance between the refinement of cell structure and the growth of pores, aging at 130 °C was determined as the optimized heat treatment for SLM AlSi10Mg samples. The tensile strength along the building direction of the 130 °C aged sample was increased from 403 MPa to 451 MPa, with relatively high elongation of 6.5%.

In this study, the effects of annealing and solution aging heat treatment on the microstructure and mechanical properties of cold spray additive manufactured (CSAMed) AA2024/Al2O3 composite were investigated. The results showed that both annealing and solution aging enhanced the interfacial bonding between the deposited AA2024 particles in the composite. The tensile properties of CSAMed AA2024/Al2O3 composite were significantly improved by 13.8% for ultimate tensile strength and 47.8% for elongation after solution aging. Microstructural examination and fractographic analysis showed that the fracture mechanism between the adjacent AA2024 particles changed from brittle to ductile-dominant mode after heat treatment. However, the interfacial bonding between the AA2024 and Al2O3 particles cannot be improved. For the improvement of mechanical properties, the solution aging was slightly better than annealing. In addition, low-temperature annealing greatly reduced the anisotropy of the mechanical properties of CSAMed AA2024/Al2O3 composite.

Regarding the as-cast Mg-9.5Gd-4Y-2.2Zn-0.5Zr alloy, the effect of heat treatment on its properties at room temperature (RT), as well as the mechanical properties and microstructure evolution of various peak-aging samples at different tensile temperatures were discussed in this article. The results indicated that the optimal heat treatment process of the alloy was: 520 °C × 24 h + 200 °C × 112 h. Under this condition, the yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) at RT were: 238 MPa, 327 MPa and 2.5 %, respectively. As the tensile temperature increases, the strength increases firstly and then decreases, but the ductility increases monotonously. The microstructures evolution of 200 °C peak-aging (200PA) and 250 °C peak-aging (250PA) samples were different with the increasing tensile tenperature. When tensile test processed at 150°C, the dense β' phase and rod-shaped basal γ' phase will be formed in the 200PA sample. However, at 300 °C, the β' phases disappeared. The β' and LPSO phases in the 250PA sample coarsened gradually as the tensile temperature increased, and 14H-LPSO phases were formed during tensile at 300 °C. The 200PA sample reached the highest strength when tensile at 150 °C, which was attributed to the hindrance of the basal dislocation and non-basal dislocation slip by the prismatic β' phases and the newly formed basal γ' precipitates.

The trade-off between strength and ductility has been an enormous difficulty in the field of materials for an extended time due to their inverse correlation. In this work, friction stir processing (FSP) was for the first time performed to high-strength and high-melting-point Ni-Co based superalloy (GH4068), and enhanced strength and ductility were achieved in FSP samples. At room temperature, the FSP sample demonstrated significantly higher yield strength and ultimate tensile strength (1290 and 1670 MPa) than that of the base material (BM, 758 and 904 MPa) and advanced wrought GH4068 alloy (982 and 1291 MPa), concurrent with high tensile ductility (∼24%). Compared with the BM, 70% higher yield strength of the FSP sample results from the remarkable contribution of grain-boundary and nanotwin strengthening, which has been confirmed by the multimechanistic model studied in this work. More importantly, with increasing temperature, an excellent strength-ductility synergy was obtained at 400 °C, i.e., the yield strength of the FSP sample was increased by more than 50% compared with the BM (from 789 to 1219 MPa); more interestingly, the elongation was also significantly increased from 17.9% in the BM to 28.5% in the FSP sample. Meanwhile, the Portevin-Le Chatelier effect was observed in the engineering stress-strain curve. The occurrence of this effect may be attributed to the interaction between solutes and defects like twins and mobile dislocations. Moreover, the grain refinement mechanism of FSP samples was proved to be discontinuous dynamic recrystallization.

Strength and ductility synergy in an Mg-3mass%Al-Mn (AM30) alloy sheet was successfully improved via twin-roll casting and annealing at low-temperature. An AM30 alloy sheet produced by twin-roll casting, homogenization, hot-rolling, and subsequent annealing at 170 °C for 64 h exhibits a good 0.2% proof stress of 170 MPa and a large elongation to failure of 33.1% along the rolling direction. The sheet also shows in-plane isotropic tensile properties, and the 0.2% proof stress and elongation to failure along the transverse direction are 176 MPa and 35.5%, respectively. Though the sheet produced by direct-chill casting also shows moderate strengths if the annealing condition is same, the direct-chill casting leads to the deteriorated elongation to failure of 23.9% and 30.0% for the rolling and transverse directions, respectively. As well as such excellent tensile properties, a high room-temperature stretch formability with an Index Erichsen value of 8.3 mm could be obtained in the twin-roll cast sheet annealed at 170 °C for 64 h. The annealing at a higher temperature further improves the stretch formability; however, this results in the decrease of the tensile properties. Microstructure characterization reveals that the excellent combination of strengths, ductility, and stretch formability in the twin-roll cast sheet annealed at the low-temperature annealing is mainly attributed to the uniform recrystallized microstructure, fine grain size, and circular distribution of (0001) poles away from the normal direction of the sheet.

Using the calculation of phase diagrams approach and Scheil solidification modeling, the Al-2.5Mg-1.0Ni-0.4Sc-0.1Zr alloy was designed, intentionally with an extraordinarily high cracking susceptibility, making it prime for solidification cracking during laser powder bed fusion. This study demonstrates the ability to mitigate even the most extreme solidification cracking tendencies in aluminum alloys with only minor alloying additions of Sc and Zr, 0.5 wt.% max. Furthermore, by employing a simple direct ageing heat treatment, good tensile mechanical properties were observed with a yield strength of 308 MPa, an ultimate tensile strength of 390 MPa, and a total elongation of 11%.

Laminated multi-layer graphene/Cu–Al–Mn composites were prepared via packaged hot roll bonding process for the first time. Microscopic observation shows that the grains in the Cu–Al–Mn layers are remarkably refined. Multi-layer graphene films intermittently disperse at the interfaces between Cu–Al–Mn layers. Some small fragments of multi-layer graphene films are squeezed into the Cu–Al–Mn layer, and around them, due to the formation of in-situ Al2O3 phase and nano-twins, multi-stage and multi-phase structures are formed. Performance tests show that the composites have ultrahigh damping capacity. Within a wide temperature range of 25–300 °C, the value of damping plateau is up to 0.1 (about 10 times that of the original Cu–Al–Mn alloy). The composites also have superior tensile mechanical properties. Their tensile strength and elongation are up to 913.3 MPa and 13.4% respectively (2.5 times and 4.1 times that of the original Cu–Al–Mn alloy). Microstructural origins of the excellent comprehensive properties were discussed in detail.

The mechanical properties of TiAl alloy prepared by directional solidification were predicted through a machine learning algorithm model. The composition, input power, and pulling speed were designated as input variables as representative factors influencing mechanical properties, and multiple linear regression analysis was conducted by collecting data obtained from the literature. In this study, the R2 value of the tensile strength prediction result was 0.7159, elongation was 0.8459, nanoindentation hardness was 0.7573, and interlamellar spacing was 0.9674. As the R2 value of the elongation obtained through the analysis was higher than the R2 value of the tensile strength, it was confirmed that the elongation had a closer relationship with the input variables (composition, input power, pulling speed) than the tensile strength. By adding the elongation to the tensile strength as an input variable, it was observed that the R2 value was further increased. The tensile test prediction results were divided into four groups: The group with the lowest residual value (predicted value-actual value) was designated as group A, and the group with the largest residual value was designated as group D. When comparing the values of group A and group D, more overpredictions occurred in group A, while more underpredictions occurred in group D. Using the residuals and R2 values, the cause of the well-prediction was studied, and through this, the relationship between the mechanical properties and the microstructure was quantitatively investigated.

Laser solid forming (LSF) technology can be used to rapidly manufacture and repair high-strength steel parts with superior performance, but the value of the heat input during operation is difficult to quantify, which has a substantial impact on the microstructure and mechanical properties of the parts. A promising method to improve the forming efficiency and quality of LSFed parts is to accurately control the heat input and explore its relationship with the microstructure and mechanical properties. To remove the interference of other variables from the experiment, the dimensionless heat input Q* was introduced. The Q* values were designed in advance to calculate the experimental parameters used to perform the LSF experiment. The microstructure was observed at different regions of the sample, and its mechanical properties were analyzed. From the results, the following conclusions were drawn. The Q* value was directly related to the cooling rate and heat accumulation in the top structure, leading to the formation of different microstructures; it also modified the original structure at the bottom, affecting the subsequent thermal cycle and indirectly changing the tempered martensite morphology. The heat input also affected the mechanical properties of the sample. The hardness of the stable zone decreased with increasing Q* value, and the lowest value was 190 HV. Similarly, the tensile strength and yield strength of the LSFed samples decreased considerably with increasing Q* value, and the lowest values were 735 and 604 MPa, respectively. Only the elongation and reduction in the area increased after a slight decrease. The Q* value had a significant effect on heat treatment. When Q* = 2.9, the increase in tensile strength and yield strength after heat treatment was the largest (29% and 44%, respectively).

In the present study, the micro-mechanical behavior of CoCrFeMnNi high-entropy alloy was investigated using an in-house micro-tensile setup at room temperature and 550 °C at different strain rates. Micro-mechanical properties are compared with those obtained using a commercial macro-tensile setup to check a potential sample size effect. Results show that mechanical properties such as yield strength, ultimate tensile strength and uniform elongation are independent of the sample size. However, the total elongation-to-failure of micro-samples is found to be lower than those of macro-counterparts. Apart from this, the material exhibits serrated plastic flow, which is strain rate dependent in terms of the onset strain and shape of serrations at 550 °C. Furthermore, transmission electron microscopy investigations were performed to correlate the occurrence of serrations to the observed distinct dislocation structures. Microstructural results provide direct evidence that dislocations are curved and hence effectively pinned and unpinned at the lowest applied strain rate, which might be responsible for the occurrence of serrated plastic flow.

Biocompostable poly (glycolic acid) (PGA) crystallizes slowly under fast cooling condition, leading to poor mechanical performance of the final products. In this work, a self-nucleation (SN) route was carried out to promote the crystallization of PGA by regulating only the thermal procedure without any extra nucleating agents. When self-nucleation temperature (Ts) decreased from 250 oC to 227 oC, the nuclei density was increased, and the non-isothermal crystallization temperature (Tc) of PGA was increased from 156 oC to 197 oC and the half-life time (t0.5) of isothermal crystallization at 207 oC was decreased by 89%. Consequently, the tensile strength and the elongation at break of the PGA were increased by 12% and 189%, respectively. According to the change of Tc as a function of Ts, a three-stage temperature domain map (Domain I, II and III) was protracted and the viscoelastic behavior of the self-nucleation melt and the homogeneous melt was studied. The results indicated that interaction among PGA chains was remained in Domain IIb, which can act as pre-ordered structure to accelerate the overall crystallization rate. This work utilizes a simple and effective SN method to regulate the crystallization behavior and the mechanical properties of PGA, which may broaden the application range of resulting materials.

A dramatic improvement of strength and ductility of cast Al-2.5Li-1.5Cu-1Zn-0.5Mg-0.15 Zr alloy was obtained by the collaboration of Sc-alloying and optimized ageing scheme. Joint and independent influence of Sc-alloying and different ageing temperatures were investigated. The results revealed that a substantial increase was realized in the hardness of Sc-containing alloy, and the ageing response time was only influenced by ageing temperature. Coarse and heterogeneous δ' (Al3Li), wide δ'-precipitation free zones (δ'-PFZs), and a large amount of T1 (Al2CuLi) precipitates were observed in Sc-containing alloy aged at 175 °C, which resulted in superior yield strength and poor elongation. The Sc-containing alloy obtained an excellent combination of ductility (elongation = 8.2 %) and tensile strength (ultimate strength =565 MPa) suffered to 150 °C ageing for 64 h. The increase in the elongation was mainly due to the combined effect of grain refining, much finer δ', and extremely narrow δ'-PFZs (

In order to obtain a uniform and effectively toughened poly (lactic acid) film by blending with low content of poly (ethylene octene) (POE) with high elasticity, the tailored interfacial intermolecular interaction and entanglement between the two phases of the PLA/POE blend was innovatively constructed via the facile reactive melt blending process through the reaction of the epoxy/anhydride groups grafted on the POE chains with the end groups of PLA chains (PLA/GPOE-MPOE). It was observed that POE domains were embedded tightly in PLA matrix with a fuzzy interface and abundant interface transition area, and the impact fractured surface of the blend showed an obvious plastic deformation with less occurrence of fibrillation of PLA matrix or interfacial de-bonding. Compared with neat PLA and directly blended PLA/POE blends, the PLA/GPOE-MPOE blend exhibited much higher complex viscosity/storage modulus, much lower tanδ values in the terminal region, and obvious strain-hardening behavior. The deviation in viscoelastic behavior of PLA/GPOE-MPOE from linear PLA indicated the enhanced molecular entanglement between the long-branched chains, resulting in an enhancement of the stretching ability during biaxial drawing of the blend. Uniform PLA/GPOE-MPOE films with draw ratio as high as 7 × 7 were obtained through biaxial stretching, which showed much higher tensile strength and the elongation at break than that of neat PLA and PLA/POE film. This work provides a facile method for fabricating toughening PLA films with application potentials.

Combined with the topology optimization, additive manufacturing can be used to fabricate metal parts with complex shapes. However, due to the geometrical variations and microstructure heterogeneities of the additively manufactured metal parts, new standards with the use of miniature specimens are required for the evalutation of the spatial distribution of mechanical properties throughout the parts. Here, we conduct a systematic investigation on tensile and fatigue properties of selective laser melted Inconel 718 specimens with different thicknesses ranging from 0.1 mm to 1 mm. A “microstructure unit” that can well reflect the microstructure characteristic of selective laser melted materials is defined. The results reveal that premature necking with a dramatic drop in uniform elongation occurs if the ratio (t/d) of specimen thickness (t) to the "microstructure unit" size (d) is less than one. Premature necking is mainly attributed to the transition of strain localization behavior. We also propose a probabilistic statistical model for fatigue limit prediction based on the available fatigue data. It is recommended that the criterion of t/d ≥ 4 should be satisfied to ensure that the yield strength, the uniform elongation, and the fatigue limit determined by the miniature specimens are comparable with those determined by standard specimens. The findings may provdie a guide to the establishment of miniature specimen-based standards toward the qualification of additively manufactured metal parts.

The property evaluation of Aluminum alloys a quite a challenging task and is an essential one to achieve improved mechanical and metallurgical properties during casting. This paves the way for the present research, in which the casting of commercial A356 and A319 Al alloys have been performed under stationary and vibratory state. The vibrational recurrence has been varied between 0 Hz and 400 Hz with a constant amplitude of 15 μm during casting. Thereafter, the quality of both casted materials has been evaluated by measuring their yield strength, ultimate tensile strength and % elongation. Experimental results revealed that the higher intensity of oscillation improves mechanical properties with the reduced grain size of α-Al. It has been also observed that the fraction of nucleation sites is increased due to the vibration.

The microstructure, phase composition, texture, and tensile properties of Ti48Al2Cr2Nb5Ta alloy prepared by laser additive manufacturing (LAM) were all investigated in detail. The microstructure of the alloy is constituted of α2(Ti3Al), γ(TiAl), and β/B2 (β ordered to B2) phases, according to the results. The microstructure changes from lamellar structure to lamellar structure divided by massive β/B2 phase when the laser power increases from 1.0 kW to 2.2 kW. Furthermore, when the laser power is 2.2 kW, the content of the β/B2 phase achieves its highest value (9.43%), whereas when the laser power is 1.8 kW, the content of the α2 phase reaches its maximum value (9.43%). The crystal texture of the γ(111) and α2(0001) orientations strengthens as laser power increases. Tensile characteristics demonstrate that the 1.4 kW alloy has the best tensile strength and elongation at room temperature and 750 °C, with values of 677 MPa, 651 MPa, and 1.8%, 2.2%, respectively. However, when compared to other alloys, the 1.4 kW alloy's tensile strength and elongation at 850 °C are slightly lower (538 MPa 13%).

In this work, biocomposites based polylactic acid (PLA) filled with piper betle fiber (PBF) were successfully synthesized by solvent cast-film method using chloroform as the solvent. The PBF was treated with 7% NaOH. The biocomposites were loaded separately with untreated and treated PBF at 1 to 3 wt% and investigated for tensile properties and morphological of fractured surfaces. Tensile strength and modulus elasticity of biocomposites were increased with addition of betel particles and found to be higher than the matrix. Furthermore, the alkali treatment of PBF had considerably improved tensile and modulus of biocomposites compared to those of biocomposites with untreated PBF. A contrary trend was found in the case of elongation at break. However, biocomposites with treated PBF had greater elongation compared to those of biocomposites with untreated PBF. These results were identified by fracture examination with scanning electron microscopy (SEM). SEM observations showed the good bonds formed between treated PBF and PLA. This indicated by less cavity and roughness on biocomposite fractured surface with treated PBF.

Background/Aim: Appropriate selection of suture material is a crucial step in oral, maxillofacial and periodontal surgery for uneventful healing. We have scarcity of comprehensive studies comparing mechanical properties of commonly used suture material in oral surgeries. The present in vitro study sought to evaluate the effect of saliva on the strength, elongation and stiffness of the commonly used suture material over a period of two weeks. Methods: Three suture materials Silk (SL), polyglactin 910 (PG) and polypropylene (PP) were used in 4-0 gauge. A total of 120 suture samples (40 from each material) were used for the experiment. Artificial saliva was mixed with human serum in 1:1 concentration and maintained at pH of 7.4 to 8.1 to simulate oral environment. All samples were tested at pre-immersion (baseline), 3rd, 7th and 14th day post-immersion periods. Universal testing machine was used to test the selected mechanical properties. The collected data were subjected to statistical analysis. Results: The distribution of mean baseline strength and percentage elongation was significantly higher in PP group (P-value

The effects of deep cryogenic treatment (DCT) on the tensile property and microstructure of Mg-9Gd-4Y–2Zn-0.5Zr(wt.%) alloy were investigated by comparing the alloy treated by solution treatment, deep cryogenic treatment and aging treatment (ST + DCT + AT) and that treated by solution treatment and aging treatment (ST + AT). The lamellar 14H-type long-period stacking ordered (14H-LPSO) in grain was precipitated in the alloy treated by ST + AT. However, the particle and needle-like Mg5RE (RE = Gd, Y) phases instead of the lamellar 14H-LPSO were precipitated, and a high-density dislocation existed in the alloy treated by ST + DCT. The greater ultimate tensile strength (UTS) and yield strength (YS) of the alloy treated by ST + DCT + AT were obtained because of the precipitation of the Mg5RE phases. The trend, the UTS and YS firstly increased then decreased with the increasing of soaking time, is corresponding to the volume fraction increasing and size-coarsening of Mg5RE precipitates, respectively. The greater elongation (EL) was obtained after the short-time DCT for 0–2 h (DCT0h-DCT2h) and the smaller EL was obtained for the long soaking time (>DCT2h). The fracture mode of the samples is all quasi-cleavage fracture.

A recyclable thermoplastic polyurethane (TPU)/Silicone thermoplastic vulcanizate (TPV) consisting of TPU, Silicone, and additives (i.e. crosslinking agent, antioxidant, compatilizers, and processing aid) with high tensile strength (10.0 MPa), good elongation (322%), low abrasion rate (0.11%), proper hardness (Shore A83), and low static/kinetic friction coefficient (0.72/0.61) has been successfully manufactured. Moreover, we have also prepared the prototype for bands of smart bracelets based on lab-made TPU/Silicone TPV, demonstrating that it is a highly potential recyclable material for wearable devices.

Cu content has been successfully optimized in a thixo-cast and directly aged (T5-treatment) Al–7Si–0.5Mg (wt.%) alloy. Even after the 0.5% Cu addition, plate-like Al2Cu (θ’) phases, which contribute to high strengths and large plasticity, are precipitated. The formation of a large fraction of Cu-containing brittle phases could be suppressed as well. Then, the Al–7Si–0.5Mg–0.5Cu alloy exhibits high ultimate tensile strength, 0.2% proof stress, and elongation to failure of 296 MPa, 209 MPa, and 8.8%, respectively. This results in a high quality index similar to that of solution-treated and subsequently aged (T6-treated) Al–7Si–Mg alloys. A Cu addition over 1.0% further improves the strengths; however, this leads to poor ductility because of the high fraction of Cu-containing brittle phases.

Increasing the toughness of poly(lactic acid) (PLA), i.e., simultaneously increasing both the tensile strength and ductility, remains a major challenge. In this study, fully bio-based PLA blends with polydecalactone (PDL)-grafted cellulose copolymer (CgPD) were prepared and comprehensively analyzed to enhance the toughness of the PLA matrix. The blends were found by FT-IR and solid-state 1H NMR to be physically intact and miscible at the sub-twenty-nanometer scale. The WXRD and DSC analyses indicated that the addition of the alkyl-branched CgPD imparts a more structurally disordered PLA mesophase state to the prepared PLA_CgPD bio-blends. UTM analysis was used to characterize the macroscopic mechanical properties of the PLA_CgPD bio-blends. Both the tensile strength and elongation properties were simultaneously improved with the addition of 1 wt% CgPD loading amount to PLA (PLA_CgPD1). This study experimentally demonstrates that the enhanced mechanical properties of PLA_CgPD1 are closely related to the existence of more ordered PLA mesophases induced by the introduction of an optimal amount of CgPD into the PLA matrix.

Stainless steel has good mechanical properties compared to other materials for strength and hardness, usually it will increase in hardness after hardening or forging. The purpose of this study was to obtain information about: The value of hardness and tensile strength of martensitic stainless steel forging with various deformations and cooling. The research method used is an experimental method, namely by forging on martensitic stainless steel with variations in deformation and cooling rate. Variations of forging deformation used are 25%, 50%, and 75%. The cooling media used are water, oil and air. The results of forgings with various cooling media were tested for tensile strength and tested for hardness using the Rockwell C (HRC) method. It was found that the higher the value of forging deformation, the higher the value of strength and hardness of martensitic stainless steel. This is because more and more martensite structures are recrystallized. In addition, it was also found that water and air cooling media gave an increase in the hardness of martensitic stainless steels. This is influenced by the cooling rate, where the higher the cooling rate, the more martensite structures formed, thus increasing the hardness value. The increase in hardness value is proportional to the increase in yield strength and tensile strength.

Graphene oxide nanosheets reinforced Cu matrix composites were prepared using ball milling process and spark plasma sintering (SPS). Effects of ball milling times on morphology of composites powders were studied. Furthermore, microstructure evolution and properties of sintered composites were investigated. Results show that the size and shape of the composites gradually transformed from regular sphericity to flake with the increase in ball milling times. Correspondingly, the average flake diameter of Cu alloy powders increased gradually from 7.2 ± 0.5 to 25.0 ± 1.0 μm. Compared with the matrix alloy, the tensile strength of the composites increases significantly and the elongation decreases gradually. For 20 h of ball milling, the yield strength of composites increased by 35% from 126 to 170 MPa, and elongation decreases from 44 to 31%. However, for 60 h of ball milling, the tensile strength and yield strength increased to 290 and 211 MPa, respectively, while the elongation significantly descends. Besides, during the ball milling, the conductivity of composite gets a slight decrease owing to the increasing degree of powder defects.

Zinc shows promise for bone repair applications, while its strength and ductility require to be improved. Carbon nanotubes (CNTs) are exceptional reinforcements due to their superior strength, ultrahigh Young's modulus, and large aspect ratio. However, their strong agglomeration and weak interfacial bonding with the matrix are key bottleneck problems restricting the reinforcing effect. In this study, Ag nanoparticles were in situ reduced on CNTs and then the CNT@Ag powders were used to prepare Zn-CNT@Ag implants by laser powder bed fusion. Results showed that Ag reacted with Zn to form a "knot"-like AgZn3 phase. It had the same lattice structure (HCP) with Zn, which indicated a good lattice matching with the matrix, thus improving the dispersion of CNTs. More significantly, the knot played a "rivet" role and enhanced the load transfer capacity, which advantaged the CNT strengthening effects by assisting in transferring the load. Moreover, it enhanced the heterogeneous nucleation effects during solidification, which weakened the texture strength of the matrix and thus increased the ductility by improving the sliding capacity. The compressive yield strength, ultimate tensile strength, and elongation of the Zn-CNT@Ag implant were increased by 22, 26, and 17% in comparison to Zn-CNTs. Moreover, the Zn-CNT@Ag implant exhibited favorable antibacterial activity with a bacterial inhibition rate of 87.79%. Additionally, it also exhibited a suitable degradation rate and acceptable biocompatibility.

A key-factor for the industrial implementation of beam-based additive manufacturing technologies is the development of novel Al alloys characterized by enhanced hot-tearing resistance. Indeed, most of the standard Al alloys are susceptible to solidification cracking and can hardly be used to produce structural parts by laser-based additive manufacturing processes. In this study, we investigate the strategies to design high-strength Al alloys for Laser Powder Bed Fusion. The addition of Zr to the chemical composition of an Al–Mg–Si alloy (EN AW 6182) was carried out by following two different routes to promote the formation of equiaxed grains which are able to suppress hot cracking and enhance processability of the material. The first route is based on mechanical mixing of ZrH2 particles and gas-atomized Al alloy powder and on the in-situ reaction of the hydride to form Al3Zr nucleants. The second route relies on the use of pre-alloyed gas-atomized powders that feature Zr among the alloy elements. The specimens produced using pre-alloyed powder showed the best mechanical performance. After direct aging from the as-built condition, the alloy showed yield strength and ultimate tensile strength of 354 and 363 MPa, respectively, and elongation at fracture of 9.0 pct. The achieved properties are comparable to those of wrought 6182 alloy processed by conventional routes.

A one-step reactive extrusion process has been demonstrated to toughen the poly(lactic acid) (PLA) blend without sacrificing its mechanical strength and degradability. Specifically, poly(lactic acid) (PLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and the peroxide initiator were first introduced into the mixer and then heated at the elevated temperatures for triggering the grafting reaction during the extrusion. During this process, the thermal decomposition of PHBV results in the unsaturated bonds that can directly grafted onto the PLA backbones by free radical reactions. From this study, we found that PLA/PHBV blend with a mass ratio of 80/20 (PLA/PHBV) and 0.3 wt% 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPH) is an optimized condition, leading to an improved elongation at break of 15.95%, which is 3.1 times of the PLA and 1.5 times of the PLA/PHBV blend without the initiator, while tensile strength exhibited very limited decreased compared to PLA. Overall, this work presents an environmentally friendly and industrial feasible approach to prepare bio-based toughened PLA for improving the elongation at break, while retaining the tensile strength and degradability.

Effect of single-pass large-strain rolling (LSR) on microstructure and mechanical properties of Al-3Li-1Cu-0.2Er-0.1Zr alloy were investigated. After LSR process at 500 °C with three different reductions (66.7, 75.0, and 83.3%), the residual Cu-rich phases along the grain boundaries were broken and homogeneously distributed. Massive nano-particles of Al3Li, Al3(Er, Zr), and Al3(Er, Zr, Li) precipitated after LSR process. However, with the increase of LSR reduction, the microstructural inhomogeneity was increasingly obvious and massive recrystallized grains were gradually observed. Both strength and ductility were improved after LSR process at 500 °C. After LSR process with 75.0% reduction at three different temperatures (400, 450, and 500 °C), with the increase of LSR temperature, some fine grains were observed near the fibrous grains. Under the condition of LSR process with 75.0% reduction at 450 °C, the best mechanical properties were obtained, with the ultimate tensile strength of 348 MPa and elongation of 19.1%.

Hydrolyzed collagen (HC) has been extensively explored in the food sector because of its functional properties and broad availability as a low-cost byproduct. However, its widespread use as a component of edible films lacks detailed information. In this study, sodium alginate/hydrolyzed collagen (SA/HC) films with distinct loadings of HC (10, 20, and 30%) were prepared. FT-IR results suggested the formation of intermolecular chemical bonds between SA and HC. When the control sample was compared with the highest concentration of HC evaluated, it was confirmed that incorporating HC increased the maximum degradation rate temperature from 226.51 to 232.89 °C (second thermal event). The thickness of all the SA/HC films increased as a function of the HC load, and a reduction of the water vapor transmission rate (WVTR) from 1215.7 ± 71.0 to 592.4 ± 52.2 g m−2 day−1 was observed. Although SEM images showed the addition of hydrolyzed collagen led to a discontinuity in the film polymeric matrix, there was no statistically significant influence on the tensile strength. However, the elongation at break experienced a significant reduction (from 11.1 ± 7.4 to 4.0 ± 2.4%), by comparing the control sample and a 30% HC loading. In general, SA/HC films with a 10% HC loading resulted in a superior general performance, so this formulation is recommended for future food packaging studies.

The demand for magnesium (Mg) alloy with high elongation, certain strength and good degradation rate used in oil and gas exploitation filed is increasing. Based on Mg-2Gd alloy, effect of copper (Cu) addition (0.25, 0.5 and 0.75 wt.%) on microstructure, mechanical properties and degradation rate were investigated. It showed that more Mg2Cu second phases were precipitated and the grain size was refined with increasing Cu content, accompanied with texture changing from 11 2 ¯ 1 > //ED to 01 1 ¯ 0 > //ED. As a result, hardness, tensile strength, compressive strength and degradation rate were enhanced while the strain hardening rate and elongation decreased. Nevertheless, the elongation was still up to at least 20%. Overall, the comprehensive mechanical properties and degradation rate of Mg-2Gd alloy can be effectively coordinated by Cu addition.

In this study, SiCp/AZ91 composites with enhanced mechanical properties was successfully obtained by a combined process route of equal channel angular pressing (ECAP) and rolling. The effect of ECAP and rolling on the microstructure and mechanical properties of SiCp/AZ91 composites were investigated by comparative analysis. Results showed that the high-pass ECAP process effectively refined the matrix grains and dispersed the SiCp, which gave rise to the final formation of homogenous microstructure in the rolled plate. A non-basal texture with high Schmidt factors was formed by ECAP process, while after rolling it turned into basal texture with relatively lower Schmidt factors. The SiCp/AZ91 composite obtained by the combined process method exhibited superior mechanical properties (yield strength of ∼348 MPa, ultimate strength of ∼411 MPa) and improved ductility (elongation of ∼6.3%) than the composite singly processed by rolling. The enhanced mechanical properties should be contributed to the homogenized microstructure with refined grains, uniformly distributed SiCp, accumulated dislocations and transferred texture.