Investigation on corrosion behavior of 7075 aluminum alloy reinforced with Ni coated duralumin powder-A hybrid metal matrix composite in acid and neutral medium

Figures & data

Table 1. Composition of the matrix and dispersion used in the fabrication of the hybrid composite.

	Elements	Cr	Fe	Cu	Mn	Zn	Ti	Si	Mg	Al
Al7075	Composition (%)	0.21	0.43	1.6	0.139	5.4	0.15	0.27	2.38	Balance
Al2024	Composition (%)	0.07	0.41	4.25	0.59	0.19	0.11	0.42	1.48	Balance

Figure 1. PDP plots for the corrosion of the Al7075 hybrid composite in (a) 0.1 M HCl and (b) 3.5% NaCl.

Table 2. Tafel polarization results for the corrosion of the Al7075 hybrid composite in 0.1 M HCl and 3.5% NaCl media at different temperatures.

7075 AA Hybrid composite	Temp (K)	Ecorr (mV versus SCE)	icorr (Acm^2)	βa (mV dec^−1)	−βc (mV dec^−1)	CR (mmy^−1)
0.1 M HCl	303	−674	3.023 × 10^−3	47.9	47.8	31.77
	313	−672	3.952 × 10^−3	46.6	46.4	41.53
	323	−683	4.530 × 10^−3	43..4	40.9	47.61
3.5% NaCl	303	−746	2.533 × 10^−5	19.64	–	0.26
	313	−762	8.891 × 10^−5	20.86	–	0.93
	323	−782	12.27 × 10^−5	21.38	–	1.28

Figure 2. Nyquist plot for the corrosion of the Al7075 hybrid composite in (a) 0.1 M HCl and (b) 3.5% NaCl.

Figure 3. Equivalent circuit used to fit the experimental EIS data for the corrosion of Al7075 hybrid composite in (a) 0.1 M HCl and (b) 3.5% NaCl.

Table 3. Results of EIS measurements for the corrosion behavior of Al7075 in 0.1 M HCl and 3.5% NaCl media at different temperatures.

Al7075 hybrid composite	Temp (K)	Rs (ohm cm^2)	Rt (ohm cm^2)	L (ohm cm^2)	Rp (ohm cm^2)	Cdl (uF cm^−2)	RL	n
0.1 M HCl	303	2.250	0.840	3.03	16.67	821	2.64	0.835
	313	1.987	0.718	0.496	14.63	1190	1.76	0.891
	323	1.833	0.656	0.406	10.68	1464	1.23	0.890
3.5% NaCl	303	0.943	1666	1190	167.4	72.9	186.1	0.856
	313	0.6582	1322	897.5	115.28	75.9	126.3	0.812
	323	0.5301	644.7	408.2	97.98	78.4	115.7	0.805

Figure 4. The Arrhenius plot (ln CR versus 1/T) for the Al7075 hybrid composite in 0.1 M HCl and 3.5% NaCl media.

Figure 5. Plot of ln (CR/T) versus 1/T for the Al7075 hybrid composite in 0.1 M HCl and 3.5% NaCl media.

Table 4. The activation parameters for the Al7075 hybrid composite in both studied corrosive systems.

Al7075 hybrid composite	Ea (kJ/mol)	ΔH^# (kJ/mol)	ΔS^# (Jmol^−1K^−1)
0.1 M HCl	16.487	13.88	−140.55
3.5% NaCl	39.739	70.181	−25.43

Figure 6. Schematic representation of the corrosion of the Al7075 hybrid composite in the presence of an aqueous medium containing Cl⁻ ions.

Figure 7. SEM images of AA hybrid composites (a) Freshly polished Al7075 hybrid composite and (b) immersed in 0.1 M HCl and (c) in 3.5% NaCl.

Figure 8. 3D images of (a) freshly polished AA hybrid composites, (b) immersed in 0.1 M HCl, (c) and immersed in 3.5% NaCl.

Table 5. AFM results obtained for the Al7075 hybrid composite.

Samples	Ra (nm)	Rq (nm)	Rmax
Freshly polished Al7075 hybrid composite	26.7	33.9	457
Al7075 hybrid composite immersed in 0.1 M HCl	143	194	792
Al7075 hybrid composite immersed in 3.5% NaCl	29.9	21.7	362

Data availability statement

The data that support the findings of the study are available from corresponding author, upon reasonable request.