In the present work, hot press of Cu–15 wt% Al alloys was carried out in a vacuum environment at a sintering temperature of 500 °C for 30 min with varying pressure (100–500 MPa) to densify the ...alloys. Both the density and hardness of Cu alloys were significantly increased with increasing the hot press pressure. A maximum density of ~ 94.5% ρth (theoretical density) and microhardness of ~ 6.2 GPa was achieved for Cu–Al alloy after hot press at 500 °C with 500 MPa pressure application. The XRD, SEM-EDS analysis confirms the presence of solid solution α (Cu
0.78
Al
0.22
) and γ (Cu
9
Al
4
) inermetallic phases in the sintered samples. Maximum hardness of 7.88 GPa and elastic modulus of 177.35 GPa was measured for Cu–Al alloy using nano-indentation test. It must be noted that so far in the literature a maximum hardness of 4.9 GPa was reported for Cu-based materials. The alloy was also measured with a moderately high compressive yield strength (1019 MPa), compressive strength (1106 MPa), and a reasonable amount of strain (6.6%). The wear tests revealed that the Cu–15 Al alloy hot pressed at 500 MPa pressure can exhibit better wear properties. Low coefficient of friction (COF) of 0.15 and wear rate of 0.71 × 10
−5
mm
3
/N-m was observed at a sliding speed of 0.25 m/s and high COF of 0.20 and wear rate of 4.33 × 10
−5
mm
3
/N-m were noted with further increasing the sliding speed (1.25 m/s). Further microstructural characterization of worn surfaces reveals abrasion wear as the major dominant wear mechanism. The present work clearly demonstrates the use of a high amount of hot press pressure in achieving good sinter density for Cu–15 wt% Al alloys with superior hardness, better wear and compressive strength properties.
The present work investigates the microstructure development and mechanical properties of mechanically alloyed and hot-pressed copper (Cu)-
X
wt pct aluminum (Al) (
X
= 0, 3, 5, 10, 15) alloys. The ...morphology of the ball-milled Cu-Al powders changed from coarse flaky structure to small hard agglomerates with the addition of Al. It was observed that the density of Cu-Al samples varied between ~ 95 and 98 pct of theoretical density (
ρ
th
) after hot pressing (Temperature: 500 °C, Pressure: 500 MPa, Time: 30 min). The crystallite size of Cu-Al samples decreased for both the milled powders and hot-pressed samples. The XRD and SEM-EDS analyses of the hot-pressed samples confirmed the presence of α-Cu solid solution phases for the Cu alloyed with Al up to 5 wt pct. On the other hand, further addition of Al to Cu leads to the formation of both intermetallic compound (Cu
9
Al
4
) and solid solution phase. The nano-indentation tests indicated a significant increase in hardness (2.4 to 7.9 GPa) and elastic modulus (121.1 to 177.4 GPa) of Cu-Al alloys. The Cu-Al alloys were measured with very high compressive strength (813.8 to 1120.2 MPa) and the compressive strain varied in the range of 29.81 to 5.81 pct.
The present work explores the effect of aluminium (Al: 0, 3, 5, 10 & 15 wt%) addition on wear behaviour of copper (Cu). The Cu-Al alloys were fabricated via mechanical alloying and high-pressure hot ...press. In fact, high-pressure processes are beneficial as they result in obtaining fine microstructure and property enhancement. Depending on the amount of Al, the microstructure of hot pressed samples (Cu with Al up to 5 wt%) consisted of copper-rich solid solution phase (Cu0.92Al0.08) and the presence of both Cu0.78Al0.22 and Cu9Al4 intermetallic phases for Cu containing high amount of Al (≥10 wt%). The relative density of Cu-Al alloys varied between ∼95 and 98% and the hardness of Cu enhanced significantly from 1.32 to 6.16 GPa with Al content. The coefficient of friction (COF) (0.54 to 0.16) and wear rate (18.26 × 10−5 to 0.92 × 10−5 mm3/N-m) of Cu decreased with the addition of Al. A transition in wear mechanisms of Cu was observed with Al. In case of pure copper, adhesion was the major wear mechanism. Adhesion and tribo-oxidation controlled the wear of Cu alloyed with Al (up to 5 wt%). Oxide layer formation influenced the wear of Cu-10Al, while abrasion was the predominant wear mechanism for Cu-15Al. These results clearly indicate the advantage of large amount of Al addition to achieve better wear resistance of Cu.
•Highly dense Cu-Al alloys were processed via powder metallurgy.•The hardness Cu enhanced significantly from 1.32 to 6.16 GPa with Al addition.•Both COF and wear rate of Cu decreased with the addition of Al.•Adhesion was the major mechanism for pure copper.•Adhesion and third body wear (wear debris/oxide layer) controls the wear of Cu alloyed with Al (up to 10 wt%).•Abrasion was the predominant wear mechanism for Cu-15wt% Al.
The effect of ZrB2 (1, 3, 5, 10 wt%) reinforcement on two-body abrasion wear properties of Cu was studied using pin-on-disc wear tester. The relative density of Cu–ZrB2 composites varied in the range ...between 96.0 and 99.7%, and in particular, relative density of copper was lowered with the addition of ZrB2. Among all the composites, Cu–10ZrB2 showed maximum hardness (1.25 GPa) and yield strength (261 MPa). However, the improvement of mechanical properties of Cu with ZrB2 was marginal. On the other hand, the ZrB2 addition significantly affected the wear properties of Cu. The steady-state coefficient of friction (COF) of Cu was reduced from 0.56 to 0.16 with the addition of ZrB2. Pure Cu exhibited a high wear coefficient (17.33 × 10−2) due to its softness and high ductile nature. The abrasive wear resistance of Cu was considerably improved with the addition of ZrB2 (up to 3 wt%) by resisting the cutting forces of SiC abrasives (counterbody). A low wear coefficient of 2.4 × 10−2 was evident for Cu–3ZrB2 composites and the wear was reduced by 7.33 times compared to pure Cu. Further addition of ZrB2 reinforcement lowered wear resistance of Cu composites. Nevertheless, the wear resistance of Cu composites was substantially better than pure Cu. The wear mechanisms were proposed based on microstructural analysis of worn surfaces of Cu–ZrB2 composites, SiC emery paper (counterbody) and wear debris. The present study demonstrates the advantage of selecting ZrB2 as reinforcement in improving the abrasion wear resistance of Cu.
•The relative density of Cu–ZrB2 composites varied in between 96.0 and 99.7%.•Cu–10ZrB2 showed maximum hardness (1.25 GPa) and yield strength (261 MPa).•With the addition of ZrB2, the COF of Cu was reduced from 0.56 to 0.16.•Pure copper was measured with high wear coefficient (17.33 × 10−2).•Low wear coefficient (2.4 × 10−2) was evident for Cu–3ZrB2 composites.
In this work, porous tantalum scaffolds (having porosity up to ~ 71%) were prepared via space holder technique at a lower sintering temperature of 1300 °C. Depending on the amount of porosity, the ...elastic modulus, yield and compressive strength of porous tantalum scaffolds were found to vary in the range of 1–7 GPa, 4–11 MPa and 22–30 MPa, respectively. Finite element simulation results revealed that tantalum scaffolds with 30% porosity were best suited for hip joint replacement applications as the developed von Misses stresses and displacement of implants under given loading conditions were within safe limits for these scaffolds. The electrochemical behavior of scaffolds was evaluated using the electrochemical workstation in simulated body fluid solution, and the corrosion rate of tantalum scaffolds was found to increase from 5.011 to 8.718 mils per year with increasing porosity. These studies reveal that the tantalum scaffolds are very effective for bioapplications.
The present work investigates the effect of (0–10 wt%) ZrB2 reinforcement on densification, mechanical, tribological and electrical properties of Cu. The consolidation of Cu–ZrB2 samples was carried ...out using a hot press (temperature: 500 °C, pressure: 500 MPa, time: 30 min, vacuum pressure: 1.3 × 10-2 mbar). The bulk density of the hot-pressed Cu composites decreased from 8.84 g/cc to 8.16 g/cc and the relative density of samples lowered from 98.6% to 92.1% with the addition of ZrB2. The incorporation of hard ZrB2 (up to 10 wt%) improved the hardness of Cu (1.32–2.55 GPa). However, the yield strength and compressive strength of Cu composites increased up to 5 wt% ZrB2, and further addition of ZrB2 lowered its strength. The yield strength of Cu samples varied from 602 to 672 MPa and the compressive strength between ~834 and 971 MPa. On the other hand, the coefficient of friction (COF) (from 0.49 to 0.18) and wear rate (from 49.3 × 10-3 mm3/Nm to 9.1 × 10-3 mm3/Nm) of Cu–ZrB2 samples considerably decreased with the addition of ZrB2. Significantly low wear was observed with Cu-10 wt% ZrB2 (Cu-10Z) samples, which is 5.41 times less than pure Cu. As far as the wear mechanisms are concerned, in pure Cu, continuous chips (wear debris) were formed during sliding wear by plowing. Whereas the major amount of material loss was occurred due to the plowing mechanism with discontinuous and short chip formation for Cu–ZrB2 composites. The electrical conductivity of Cu–ZrB2 samples decreased from 75.7% IACS to 44.1% IACS. In particular, Cu with ZrB2 (up to 3 wt%) could retain the conductivity of 66.8% IACS. This study reveals that the addition of ZrB2 (up to 3 wt%) is advantageous to have a good combination of properties for Cu.
•Relatively higher density was achieved for hot pressed Cu and Cu-15Al alloy.•The hardness of Cu was significantly improved with the addition of Al.•Drastic reduction in corrosion of Cu with addition ...of 15 wt% Al.•The formation of protective layer improved corrosion resistance of Cu-15Al alloy.
Higher density of 98.66 and 94.60% ρth (theoretical density) was achieved for hot pressed Cu and Cu-15Al alloy, respectively. The microstructure of Cu-15Al alloy consists of α (Cu0.78Al0.22) and γ2 (Cu9Al4) phases. The hardness of Cu was significantly improved (from 1.32 to 6.03 GPa) with the addition of Al. Drastic reduction in corrosion of Cu-15Al (1.6 mpy) when compared to pure Cu (20.7 mpy) was noticed despite the low densification of Cu-Al. The higher impedance of Cu-15Al alloy corroborates the formation of protective layer. This work demonstrates the efficacy of high amount of Al in improving corrosion resistance of Cu.
In the present work, the effect of Al content (0, 3, 5, 10, 15 wt-%) on the microstructure, mechanical and wear properties of Cu was systematically studied. Interestingly, the core-shell ...microstructure was observed in the Cu-Al alloys or Al bronzes with different layers of α-Cu, and intermetallic phases. The Cu-Al alloys displayed good compressive yield strength of 174-653 MPa, in particular, the Cu samples with Al (upto 10 wt-%) did not show fracture upto strain of 40%. Abrasion wear was the predominant wear mechanism in pure Cu and Cu-Al alloys after sliding against SiC. The Al addition to Cu drastically decreased the wear rate (198 ×10
−3
to 3.8 ×10
−3
mm
3
N
-1
m
-1
) of Cu-Al alloys. The present work demonstrates the advantage of the addition of (5-10 wt-%) Al to Cu in achieving good combination of mechanical and wear properties of Cu-Al alloys.
