Brittle Fracture Tendency Research Articles

Microstructure and properties of low alloy CrMo steel processed with varied isothermal temperatures

The microstructure and properties of low alloy CrMo steel after isothermal treatment at different temperatures were studied. The experiment process is to rapidly cool the samples that have been held at 940 ℃ for 2 h to a salt bath furnace at different temperatures (300–500 ℃) for isothermal treatment, and then air cooling to ambient temperature. The microstructure after isothermal treatment is granular bainite, which is a mixed microstructure composed of bainitic ferrite (BF) and martensite/austenite (M/A) island. The morphology, size and volume fraction of M/A islands change with the change of isothermal temperature. The mechanical properties are also closely related to isothermal temperature. With the increase of isothermal temperature, the impact toughness and yield strength (YS) decreased. By studying the effects of different strengthening mechanisms and multiphase on YS, the results show that YS mainly depends on BF. According to the SEM and EBSD characterization of the fracture, it is found that the stress in the sample is mainly concentrated near the M/A, which makes the crack easy to initiate on the M/A island or its interface. The brittle fracture tendency of materials is related to M/A island. The larger the size of the M/A island, the more likely brittle fracture will occur and the less ductile it will be.

Effect of the notch depth on fracture behavior of TC4 titanium alloy sheets

To evaluate the low-stress brittle fracture of TC4 titanium alloy sheet structures, the effect of notch depth (d) on the fracture behavior of the 1.8 mm thick TC4 titanium alloy sheets was investigated combied with tensile tests and digital image correlation method. The results show that the ductile–brittle transition (DBT) occurs with increasing notch depths. Ductile fracture occurs for the notched samples with d = 0.5–1.5 mm, and a uniform plastic deformation stage is observed in the load–displacement (P-L) curves, and there are stretch zone and the stable crack propagation zone in the fracture surfaces. Brittle fracture occurs for the notched samples with d = 3.0–5.0 mm, and there is only the linear elastic stage in the P-L curves, and no stretch zone in the fracture surfaces. The samples at the middle notch depths (d = 2.0–2.5 mm) are in the transition from ductile to brittle fracture, and there exists the elastoplastic deformation stage in the P-L curves, and the stretch zone and stable crack propagation zone are both decreased. The analysis of notch fracture parameters shows that fracture of notched samples is controlled by the stress concentration and the stress field intensity of an imaginary crack with the same notch depth. The effect of crack gradually increases with increasing d, which results in increased brittle fracture tendency. Moreover, the fracture energy γf can characterize the DBT of notched TC4 titanium alloy sheets, and the γf is proportional tothe ratio of critical plastic zone size to d (rpc/d). Finally, the rpc/d is proposed to characterize the DBT of the notched TC4 titanium alloy sheets, and the criterion of the DBT for the notched TC4 titanium alloy sheets is obtained.

Effect of α Phase on Dynamic Mechanical Properties and Failure of Ti-4Al-5Mo-5V-5Cr-1Nb Alloy after Two-Stage Aging

This work studied the high strain rate behavior of the Ti-4Al-5Mo-5V-5Cr-1Nb (Ti-45551) alloy after two-stage aging, with dynamic tension tests conducted using the split Hopkinson tensile bar. The results show that the microstructure, especially the size and distribution of the α phase, significantly affects the mechanical and failure behaviors of the Ti-45551 alloy under dynamic loading. As the strain rate increases, increasing trends can be observed in both ductility and strength, which is intimately related to the activation of the dislocation slip in the α phase. Moreover, obvious strain softening was found in the Ti-45551 alloy under dynamic loading. In this study, the microstructure observations suggest that dislocation slips are highly active in the α phase under dynamic loading. Fractographic characterization of the fracture surfaces under dynamic loading reveals a uniform distribution of ductile dimples, which indicates that a uniform distribution of the nano-scale α phase can effectively reduce brittle fracture tendency. Our studies provide a comprehensive picture of how strain rate drives dynamic plasticity and failure mode in the Ti alloy.

Artificial neural network molecular mechanics of iron grain boundaries

This study reports grain boundary (GB) energy calculations for 46 symmetric-tilt GBs in α-iron using molecular mechanics based on an artificial neural network (ANN) potential and compares the results with calculations based on the density functional theory (DFT), the embedded atom method (EAM), and the modified EAM (MEAM). The results by the ANN potential are in excellent agreement with those of the DFT (5% on average), while the EAM and MEAM significantly differ from the DFT results (about 27% on average). In a uniaxial tensile calculation of ∑3(11¯2) GB, the ANN potential reproduced the brittle fracture tendency of the GB observed in the DFT while the EAM and MEAM mistakenly showed ductile behaviors. These results demonstrate the effectiveness of the ANN potential in calculating grain boundaries of iron, which is in high demand in modern industry.

Artificial Neural Network Molecular Mechanics of Iron Grain Boundaries

This study reports grain boundary (GB) energy calculations for 46 symmetric-tilt GBs in α-iron using molecular mechanics based on an artificial neural network (ANN) potential and compares the results with calculations based on the density functional theory (DFT), the embedded atom method (EAM), and the modified EAM (MEAM). The results by the ANN potential are in excellent agreement with those of the DFT (5 % on average), while the EAM and MEAM significantly differ from the DFT results (about 27 % on average). In a uniaxial tensile calculation of Σ3(1‾12) GB, the ANN potential reproduced the brittle fracture tendency of the GB observed in the DFT while the EAM and MEAM showed mistakenly showed ductile behaviors. These results demonstrate the effectiveness of the ANN potential in grain boundary calculations of iron as a fast and accurate simulation highly in demand in the modern industrial world.

Comparative evaluation of properties of paracetamol tablets formulated with three local starches as binders

This study was carried out to comparatively evaluate the tableting and release characteristics of paracetamol tablets prepared with three indigenous starches as binder. These parameters were compared with those tablets prepared with Maize starch BP as standard. Starches currently being used in pharmaceutical industry are largely imported into the country, hence there is the need to source for some indigenous starches whose binding properties would sufficiently ameliorate the brittle fracture tendency that has been a major problem in tableting. Starches from African bitter yam (Dioscorea dumetorium), cocoyam (Colocasia esculenta) and cassava (Mannihot utilissama) tubers were extracted and characterized with Maize starch BP as standard. Their true particle densities were determined with the specific gravity bottle method. Viscosities of the starch mucilage were also determined. The mucilage of each of these starches was used as binder at concentrations (1, 1.5, 2 and 2.5% w/w) per tablet in the formulation of paracetamol granules. The granules were compressed to tablets with and without a centre hole at varying compression loads (3, 4 and 5 arbitrary units). The tablets were flat faced with mean diameter of 12.1 ± 0.02 mm and mean thickness 4.1 ± 0.02 mm. The tablets’ tensile strength (T), brittle fracture index (BFI), packing fraction (Pf), disintegration time (DT) and dissolution profiles were determined. The centre hole in the tablet served as a model defect to represent void that are formed in the tablet during compression due to air entrapments. The results showed that there was no statistically significant difference in the physicochemical characteristics of the tablets whose granules were prepared with the 3 test starches and those prepared with the standard maize starch BP (p > 0.05). There was a general increase in the tablet viscosities as the mucilage concentration increased. Cassava starch mucilage was more viscous hence expected to impact more plasticity to the granules. Tablet tensile strength (T) increased with increase in the binder concentration but was more marked with tablets produced with cassava starch mucilage. At all m binder concentrations, cassava starch produced tablets with lowest BFI and highest Pf compared to the other starches including maize starch BP. Increase in compression load resulted in tablets with increase in T, BFI, Pf and DT. The increase in BFI is attributed to increase in die wall stress on the tablet at the point of ejection during compression. All the tablets released between 79.2 - 89.6% of the drug in 45 min. Although drug release was influenced by increase in binder concentration, the release rate was nevertheless significantly affected by the types of starch binders under investigation. The results permit the conclusion that the three (3) sourced indigenous starches (African bitter yam, cocoyam and cassava) could be substituted for maize starch BP as binder in the preparation of paracetamol tablets.Keywords: Cassava starch, African bitter yam starch, cocoyam starch, binder, tablet properties, paracetamol

Effect of Substrate Pre-carburizing on Properties of TiN (Ti) Hard Coatings Deposited on Ti-6Al-4V Alloy

Interface fracture often occurs in systems of soft substrate and hard coatings during the service process, which is related to the weak interface strength and the unstable expansion of cracks along the interface induced by the residual thermal stress. The residual thermal stress mainly comes from the mismatch of thermal physical properties between matrix and hard coatings. In this study, a gradient carburized layer was prepared on TC4 substrate before the deposition of TiN(Ti) coatings using double glow plasma carburization. And then the mono- and multilayer TiN(Ti) coatings were synthesized on the carburized layer, forming composite hard coatings. The effect of substrate carburizing on properties of coatings was studied. The results show that the composite coatings' hardness can be increased nearly 2 times and the bonding strength is enhanced to over 80 N, compared with that of mono-and multilayer TiN(Ti) coatings. Also the interface brittle fracture tendency is restrained obviously by the hardened substrate, and the coordinative deformation ability of the coating at extra load is optimized. The composite coating composed of pre-carburized layer and TiN hard coating shows a higher strength and toughness.

Investigation of the Origin of Coarse-Grained Bainite in X70 Pipeline Steels by EBSD Technique

Structural inhomogeneities that occurred in pipeline steels during controlled rolling and were identified as elongated regions of coarse-grained bainite were found to promote a tendency for brittle fracture of these steels. In particular, it was shown by tint etching, with subsequent analysis in polarized light with the light-optical microscope, that their volume fraction exhibited a perfect correspondence with the failure behavior. The aim of the present investigation was to comprehensively characterize the microstructure and the local texture of these regions using the EBSD technique and thereby clarify their origin. It was shown that, whereas the local texture of fine-grained regions corresponded well to the macroscopic texture of the steel band, the local texture of the structural inhomogeneities corresponds to certain minor components of the macroscopic texture. The grains of the parent austenite, from which these inhomogeneities have been produced, had orientations concentrated close to the brass component of austenite rolling texture. Hot deformation of the austenite leads to a strong variant selection (predominant realization of certain lattice orientations among plausible orientations of α-phase) during phase transformation of these grains, that result in a significant increase of the bainite packet size. Formation of bainite in the upper temperature range of bainite transformation, in its turn, leads to such a variant pairing that low-angle boundaries are formed predominantly both inside and between the packets. This further enlarges the effective grain size and correspondingly enhances the deteriorative effect of the structural inhomogeneity.

ВЛИЯНИЕ РАЗЛИЧНЫХ РЕЖИМОВ ПОСЛЕСВАРОЧНОЙ ТЕРМИЧЕСКОЙ ОБРАБОТКИ НА СТРУКТУРНУЮ И МЕХАНИЧЕСКУЮ НЕОДНОРОДНОСТЬ СВАРНЫХ СОЕДИНЕНИЙ СРЕДНЕЛЕГИРОВАННЫХ СТАЛЕЙ, ВЫПОЛНЕННЫХ РОТАЦИОННОЙ СВАРКОЙ ТРЕНИЕМ

Rotational friction welding is one of the promising technologies for the creation of high-quality welded joints, which is widely used in the pipe industry when producing wide nomenclature drill pipes of medium-carbon alloy steels. Despite the long-term application of this method by the Russian enterprises manufacturing this type of products, there are few published data in the scientific literature aimed at the detailed study of structural and mechanical heterogeneity of such compounds, including after various modes of their heat treatment. The authors evaluated the structural and mechanical heterogeneity of welded joints of 30HGSA-40HN2MA steels tested to produce geological exploration drill pipes in the initial state and after the application of various temperature-time modes of induction annealing. The paper presents the results of hardness measurement in different areas of welded joint and the results of rupture test and impact-viscosity test. During the study, the authors determined the peculiarities of phase transformations occurring in welded materials depending on the temperature and time factors that affected the degree of mechanical heterogeneity of the annealing zone and the level of mechanical properties, including the nature of impact fracture. It is shown, that, during the rupture tests, the mechanical properties of welded joints of 30HGSA-40HN2MA steels generally depend on the properties of thermomechanical impact zone of 30HGSA steel as the weakest area where the deformation is localized and the rupture occurs. The authors determined the formation of hardening structures during the induction annealing from the 40HN2MA steel side influencing the tendency for brittle fracture of the welded joint area. Optimal modes of heat treatment of this welded joint combination from the position of full-strength and reliability of the structure are recommended.

Study of Hot Salt Stress Corrosion Crack Initiation of Alloy IMI 834 by using DC Potential Drop Method

DC potential drop technique was employed during the slow strain rate tests to study the hot salt stress corrosion crack (HSSCC) initiation at 300 and 400 °C. Threshold stresses for HSSCC initiation were found to about 88 % of the yield strength at both temperatures, but the time from crack initiation to final failure (Δtscc) decreased significantly with temperature, which reflects larger tendency for brittle fracture and secondary cracking. The brittle fracture features consisted of transgranular cracking through the primary α grain and discontinuous faceted cracking through the transformed β grains.

POTENTIAL OF BRACHYSTEGIA EURYCOMA GUM IN AMELIORATING BRITTLE FRACTURE DURING TABLETING

The aim of the present study is to investigate the potential of Brachystegia eurycoma gum in ameliorating brittle fracture (i.e., lamination and capping) a problem often encountered during tableting. Granules of metronidazole (test drug) were prepared by wet granulation technique using Brachystegia eurycoma or acacia gum at concentrations of 2.5, 5.0, 7.5 or 10%w/w. The resulting granules were evaluated for packing and flow properties. Granules were compressed into tablets with and without a centre hole (as in- built defect) using a compression load of 2.0 arbitrary unit on the load scale. The tablets were evaluated for tensile strength and the data was used to calculate the brittle fracture index (BFI). The compressibility index which is a measure of ease of compaction of the granules upon tapping was < 23.5% while all granules were free flowing with angle of repose <36.90. Increase in binder concentration led to an increase in Pf and T values irrespective of the type of the gum binder used in the formulations. Generally, increasing the binder concentration at a given compression load resulted in a decrease in the brittle fracture tendency of the tablets. For instance, at a binder concentrations of 2.5% w/w the BFI for Brachystegia eurycoma and acacia gum were 0.13 and 0.10 respectively while their corresponding values at binder concentration of 7.5% w/w were 0.06 and 0.08. The study has shown that Brachystegia eurycoma gum is an effective binder that produces harder tablets with low brittle fracture tendency.

Ageing of forged superaustenitic stainless steel: Precipitate phases and mechanical properties

Abstract Cast superaustenitic stainless steel (SASS), of composition 19 wt% Cr, 20 wt% Ni, 7.5 wt% Mo and 0.37 wt% N, is hot forged at 1200 °C. The forging was then solutionized at 1250 °C and aged for 1 h and 10 h at different temperatures in the range of 500–1000 °C. Effect of these treatments on (i) hardness and (ii) fracture toughness based on impact energy is reported. Chi is formed from low temperatures up to 800 °C, and sigma at temperatures above 900 °C. A model is proposed to illustrate the dissolution of chi and sigma in austenite at elevated temperatures. Compared with chi, sigma contains more Mo. Toughness decreased with increasing amounts of chi and sigma precipitates. However, in the temperature range of 850–950 °C, low toughness was observed for relatively a short ageing time, although virtually the volume of sigma phase is very low. This is attributed to the presence of incoherent sigma in austenite matrix. Fractographs of the impact-tested samples indicated an increased tendency for brittle fracture with increasing ageing temperatures (increase in sigma content). Thermodynamic calculations substantiated (i) EDS results of composition of secondary phases present in the aged SASS and (ii) the proposed model. From these studies it is concluded that sigma is enriched in Mo at 900 °C and can be as detrimental to toughness of SASS as chi or carbides and nitrides.

Effects of Sc Addition and Annealing Treatment on the Microstructure and Mechanical Properties of the As-rolled Mg-3Li alloy

The microstructures and mechanical properties of the as-rolled Mg-3Li and Mg-3Li-1Sc (wt%) alloys before and after annealing treatment have been investigated. Results show that the grains are refined evidently and the recrystallization temperature is improved for more than 100°C by adding 1 wt% Sc into the Mg-3Li alloy. After complete recrystallization, both the strength and ductility of the Mg-3Li alloy are improved evidently with the addition of minor Sc. The brittle fracture tendency of Mg-3Li-1Sc alloy also reduces obviously.

Boron carbide-reinforced alumnium 1100 matrix composites: Fabrication and properties

With the increasing trend in the use of light-weight functional material in emerging industrial applications, understanding the fabrication of aluminum–boron carbide (ABC) composite is becoming needful. In this context ABC composites up to 25 wt.% boron carbide (B 4C) particulate reinforcement in alumnium 1100 matrix were prepared at 873 K and the resulting microstructure and physico-mechanical properties were studied. Dark-field images showed the continued existence of porosities. The density and electrical conductivity decreased from 2.52% to 1.8% and from 48% to 11% of the International Annealed Copper Standard, respectively. There was an 11-fold increase in hardness with 25 wt.% B 4C addition. Although the flexure strength of the composite decreased because of transition in formation of phases at grain boundaries from ternary Al–B–C to binary Al–B, growth of Al–B and retention of boron carbides, the flexure modulus showed up to 8 times improvement with increased fraction of reinforcement. Fractographs revealed extensive damage to grain boundaries because of generated shear and particle pull-out. The tendency for brittle fracture increased with higher reinforcement fractions. The study forms the basis to commercialise ABC composites for required applications, and it is concluded that even though uncoated boroncarbide reinforcements embrittle the aluminum matrix in as-reinforced condition, improvement in other as discussed properties is significant. The study also indicates that the ductility of the metal matrix composite (MMC) may be improved by increasing the interfacial bonding and decreasing the overall porosity contents of the composite.

English

A comparative study has been carried out to investigate the binder effects of the gums ofCissus populnea&nbsp;and&nbsp;Accasia senegal&nbsp;on the mechanical properties of paracetamol tablets. Tablet mechanical properties evaluated include the packing fraction (Pf), the tensile strength (T) and the brittle fracture tendency (BFI). Varying concentrations of the gum mucilage ranging from 1 - 15% (w/v) was prepared and their relative viscosities determined. Each concentration was used to wet massed paracetamol powder to form granules. Tablets of paracetamol (500 &plusmn; 6.5 mg) were compressed at a constant compression load (7 arbitruary units on the scale). The tablets were equilibrated for 24 h before evaluation. At all binder concentrations&nbsp;A.&nbsp;senegal&nbsp;gum produced harder and more consolidated tablets than&nbsp;C.&nbsp;populnea&nbsp;as reflected by the higher T and Pf&nbsp;values respectively. For instance, the T and Pf&nbsp;values of the tablets at binder concentration of 10% (w/v) were 0.69 MNm-2&nbsp;and 0.47 (A.&nbsp;senegal) and 0.57 MNm-2&nbsp;and 0.23 (C.populnea), respectively. On the contrary, an increase in binder concentration generally resulted in a decrease in BFI values and this decrease was more marked with&nbsp;C.populnea. The study showed that&nbsp;A.&nbsp;senegal&nbsp;mucilage displayed better tableting characteristics and higher tendency for ameliorating capping tendency. Both mucilages have the potentials for substitution as binder for the more expensive starches in tablet formulation. &nbsp; Key words:&nbsp;Cissus populnea,&nbsp;Acassia senegal&nbsp;gum, paracetamol tablet, tensile strength, brittle fracture index, packing fraction, binder effect.

Relationship Between Slugging Pressure and Brittle Fracture Tendency – A Case Study for Aspirin Tablets

Objective – Slugging is a pre-compression technique for the dry granulation of hydrolysable drugs (e.g. aspirin). The study was carried out to relate the slugging load to the hardness of the granules and the brittle fracture tendency of the final (recompressed) tablets. Method – Varying compression load were applied to aspirin powder to form slugs, which were subsequently broken down to form granules. These were recompressed to give the final tablets. The hardness of the slugs was determined and taken as measure of the hardness of the resulting granules. The following tableting parameters were measured for the final tablets - tensile strength (T), packing fraction (Pf) and the brittle fracture index (BFI). Results - A high slugging load was associated with the formation of hard slugs and hence hard granules. Upon recompression the hardest granules formed the hardest tablets (T = 3.29MN m-2) while the softest granules formed the softest tablets (T=1.09MN m-2). In turn, the hardest tablets displayed the highest brittle fracture tendency (BFI = 0.59) compared with the softest tablets (BFI= 0.21). A positive linear correlation existed between tablet hardness (T) and BFI values (r = 0.98). Keywords: Slugging pressure, aspirin granules, tablet tensile strength, brittle fracture index > Tropical Journal of Pharmaceutical Research Vol. 4 (2) 2005: pp. 483-487

Evaluation of the binder effects of the gum mucilages of Cissus populnea and Acassia senegal on the mechanical properties of paracetamol tablets

A comparative study has been carried out to investigate the binder effects of the gums of Cissus populnea and Accasia senegal on the mechanical properties of paracetamol tablets. Tablet mechanical properties evaluated include the packing fraction (Pf), the tensile strength (T) and the brittle fracture tendency (BFI). Varying concentrations of the gum mucilage ranging from 1 - 15% (w/v) was prepared and their relative viscosities determined. Each concentration was used to wet massed paracetamol powder to form granules. Tablets of paracetamol (500 ± 6.5 mg) were compressed at a constant compression load (7 arbitruary units on the scale). The tablets were equilibrated for 24 h before evaluation. At all binder concentrations A. senegal gum produced harder and more consolidated tablets than C. populnea as reflected by the higher T and Pf values respectively. For instance, the T and Pf values of the tablets at binder concentration of 10% (w/v) were 0.69 MNm-2 and 0.47 (A. senegal) and 0.57 MNm-2 and 0.23 (C. populnea), respectively. On the contrary, an increase in binder concentration generally resulted in a decrease in BFI values and this decrease was more marked with C. populnea. The study showed that A. senegal mucilage displayed better tableting characteristics and higher tendency for ameliorating capping tendency. Both mucilages have the potentials for substitution as binder for the more expensive starches in tablet formulation.

Influence of some starch binders on the brittle fracture tendency of paracetamol tablets

The study was carried out to compare the binder effects of cassava and cocoyam starch with that of maize starch BP. The parameters investigated were the brittle fracture index (BFI), the tablet packing fraction (Pf), and tensile strength (T). Mucilages of the starches of varying concentrations; 15, 20, and 25% (w/v) were formed; their viscosities were determined and used to form paracetamol granules by wet-massing. The granules were compressed at different compression loads (arbitrary units on the load scale; 8, 9 and 9.5). At all given compression loads and at all binder concentration, cassava starch mucilages binder produced the hardest and most compact tablets with the least tendency to brittle fracture compared with cocoyam or maize starch mucilage. For instance, the BFI values at the compression load, 8 were 0.13 (tablets formed with cassava starch mucilage 20% w/v) 0.18 (tablets formed with cocoyam starch mucilage 20% w/v) and 0.35 (tablets formed with maize starch mucilage 20% w/v). Increase in compression load (8 to 9.5) increased the BFI of these tablets while an increase in binder concentration generally caused a decrease in BFI of these tablets. This decrease was less marked at higher compression load. The results indicate that cassava starch mucilage which was the most viscous, displayed the highest potential for ameliorating brittle fracture during manufacture of paracetamol tablets.

Influence of some starch binders on the brittle fracture tendency of paracetamol tablets

The study was carried out to compare the binder effects of cassava and cocoyam starch with that of maize starch BP. The parameters investigated were the brittle fracture index (BFI), the tablet packing fraction (Pf), and tensile strength (T). Mucilages of the starches of varying concentrations; 15, 20, and 25% (w/v) were formed; their viscosities were determined and used to form paracetamol granules by wet-massing. The granules were compressed at different compression loads (arbitrary units on the load scale; 8, 9 and 9.5). At all given compression loads and at all binder concentration, cassava starch mucilages binder produced the hardest and most compact tablets with the least tendency to brittle fracture compared with cocoyam or maize starch mucilage. For instance, the BFI values at the compression load, 8 were 0.13 (tablets formed with cassava starch mucilage 20% w/v) 0.18 (tablets formed with cocoyam starch mucilage 20% w/v) and 0.35 (tablets formed with maize starch mucilage 20% w/v). Increase in compression load (8 to 9.5) increased the BFI of these tablets while an increase in binder concentration generally caused a decrease in BFI of these tablets. This decrease was less marked at higher compression load. The results indicate that cassava starch mucilage which was the most viscous, displayed the highest potential for ameliorating brittle fracture during manufacture of paracetamol tablets. Key words: Cassava, cocoyam, maize starch, binder effect, tensile strength, brittle fracture index, tableting.

Anomalous effect of compression pressure on the brittle fracture tendency of α-cellulose tablets

The effect of varying the compression pressure on the brittle fracture tendency of α-cellulose and lactose tablets has been investigated. Tablet tensile strength, ( T), packing fraction, ( P f), and brittle fracture index (BFI) were determined at different compression pressures (0.82, 1.22 and 1.63 MPa). In another aspect of the study, α-cellulose and tapioca powders were mixed in various proportions to obtain powders of varying plastoelasticity. Their tableting characteristics T, P f and BFI were also determined at the different compression pressures. The polymer, α-cellulose displayed the characteristics of plastic compression—a low BFI but high T and P f values while lactose displayed the characteristics of elastic compression—a high BFI but low T and P f values. The degree of plastic compression decreased as the proportion of tapioca in the powder mixture increased from 0 to 50% w/w. Higher concentrations of tapioca >50% produced crumbly tablets at all compression pressures, thus indicating that tapioca is highly elastic. Increase in the compression pressure caused an increase in the BFI values of lactose tablets, 0.39–0.76 but a decrease in the BFI values of α-cellulose tablets, 0.38–0.09. This decrease became less pronounced as the plasticity of the powder mixtures decreased. The difference in the response of the tablets to the change in compression pressure relates to the difference in the plastoelasticity of the materials tested.